Blockchain Full Course 2026 | Blockchain Tutorial For Beginners | Blockchain Course | Simplilearn

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by simply. Let's kick things off with a little secret. You have probably heard people saying blockchain is just a trend, but the truth is blockchain is changing the world. From cryptocurrencies to supply chain management, blockchain technology is in high demand and it's not going anywhere. By the end of this course, you will have a solid understanding of how blockchain works and how it's used in various industries. So whether you want to develop blockchain apps or just understand cryptocurrencies, this course has got you covered. So here is what we'll cover in today's video. First, we'll understand what is blockchain. We'll cover what blockchain is and how it works. Next, we'll have a look at applications of blockchain where we will discover real world applications like cryptocurrencies and supply chains. Next, we'll understand the difference between public versus private blockchains. We'll also learn about mining and how proof of work validates transactions. Next, we'll explore the more energyefficient proof ofstake method. We'll also understand gas fee and how they affect Ethereum transactions. We'll get practical tips on building wallets, smart contracts, and tokens. Also, if you're looking to dive into blockchain technology and want to start with the basics, I have got something exciting for you. Check out this free blockchain course that comes with certification. This course is designed to give you hands-on experience with blockchain fundamentals like Bitcoin, Ethereum, smart contracts, and much more. So whether you're just a beginner or looking to expand your knowledge, this course is perfect for you. You'll get 6 hours of self-paced lessons plus 90 days of free access to all the content. And yes, once you complete it, you will get a completion certificate to showcase your new skills. So, if you are ready to explore how blockchain is changing the world of cryptocurrency and beyond, why not get started today? It's all completely free and it's a perfect first step to the world of blockchain development. So guys, before we dive in, here's a quick quiz question for you. The question is, which of the following best describes blockchain technology? Your options are a system for managing digital identities, a decentralized and transparent ledger for recording transaction, a traditional banking method, a type of cloud storage for data. Take a moment to think about your answer and once you're ready, we will get started. As of now, you see in the Bitcoin what we know in the Bitcoin, we already know about proof of work. One case, we know about the halfing concept. What is halfing? So now in this case you see halfing is also one of the uh concern and then we have limited supply of bitcoins. This is also we understand also we understand what is bitcoin minting. Okay. Now all these concepts we know and also I should write here the difficulty adjustment as well. difficulty adjustment and also we know about the case of nons as well. So nons is number that is used only once a random number. Now one more thing that we are using this is utxo and believe me this is you know uh I have seen many interviews where this question has been asked by the by the interviewer or the recruiter. So you should know this concept very well and we'll I promise you we'll be covering it in very easy language so that all of you have a very good understanding of this. So now you see I'm saying unspent transaction um output. So what is the full form or what is the abbreviation for this unspent transaction output? You see here UTXO. Okay. And now when I say UTXO what exactly is this? Now to understand this let's understand a uh I can say a imaginable scenario or a real life scenario. Now let's say I do have a note of 500. All of you listen this carefully. I do have a note of 500. In fact I do have a note of 500 three notes. So how much is my total amount? How much is total amount? So we are talking about fiat currency Indian rupees. So this is my physical currency and once we understand that then we'll come back to the physical currency. So total amount is what? 1,500. Okay. So I do have a 1,500. So I entered into a grocery market. So my total bill is 1,200 and I do not have any other amount apart from this. And plus I am not paying anything online as well for certain reasons. No GPA, no UPI, no card payment, nothing is there. So how I will make the payment? How I will make that payment? I do not know. I have 500 notes. Total 1,500. So how many notes I should be giving to the shopkeeper? >> Sorry. How many notes I should give to the shopkeeper? All three. All three notes. Because we know 500 multiply 3 is 1500. So I cannot go with two also. I cannot go with the uh one also. So I will be giving total all 500 into three. So with respect to this the shopkeeper will be giving me a change. Okay. Change. Now how much will be the change? So this will be 300 rupees. Correct? Okay. So this 300 rupees the combination could be u a note of 200 or note of 100 or maybe the combination could be a note of 100 a note of one more 100 or a note of 100. Okay. So this could be possibility or even any number of combinations could be there. We we can just consider anything. So basically now you see these things I give a name. What name I'm giving? Input is or I can say input is 1,500 or in this case I'll take 500 3 500 into 3 only. So input what I have given to the shopkeeper three notes of 500 what I am reing as output what I'm receiving as output one my item or when I say what is whatever I have shopped for plus I am getting 300 rupee change okay what I'm getting 300 rupee change now note this term this is what 300 this is my change that I received after my shopping okay now in this case As you see when I say 300 as a change so I'm associating this 300 with unspent transaction output. Correct? But now you will be thinking Bitcoin is not about any physical money. Bitcoin is all digital. So why do we are talking about change in something? But you see this is the beauty of the concepts. Now Bitcoin how do they follow the things? Let's consider this. So they follow the UTX2 model. As of now they follow the UTXO model and uh when you understand this you will also find that why they are following up this complicated method. But uh for certain reasons Bitcoin is falling up. So when I say UTXO model let's say I am this is I am Alice. Alice account balance is 10 bitcoin. Okay. Als take it like this. Alice and Bob. Alice account balance is 10 bitcoin. Bob's balance is 5 bitcoin. Okay. Alice and Bob we have taken here. Now what is the target? Ellis is willing to transfer some amount to Bob. Okay, that is well taken. Now when I say 10 bitcoin, this 10 bitcoin is not like a digital money. 10 bitcoin is not like a digital money. It is more like a physical money. How this is being arranged into components. What is that component? So might be you see one component is five bitcoin, one component is two bitcoin, one component is 1 bitcoin, one component is 5 + 2 is 7 8 and 2 bitcoin. Is it making total 10? Is it making total 10? 5 + 2 is 7. 7 + 1 is 8. 8 + 2 is 10. So total is 10 bitcoin. Okay. So now what I have said as of now as of s now now I have just given you a situation that we have two user one is Alice one is Bob Alice account balance is 10 bitcoin Bob's account balance is five bitcoin and then I mentioned bitcoin is also maintaining some components to form a total account balance. So this is we have taken a shape of company. Okay. Now similarly the same thing should be applied to the Bob as well. So let's say component for Bob is 3 bitcoin plus two bitcoin. Okay. Now the case is Alice is willing to transfer Bob money of I say here two bitcoin or in fact four bitcoin. Correct. Now you see from this component which component should be passed to the bob. In fact rather than making it four I make it something called as six or I make it 6.5. That will be better. Okay. Now you see so Alice wants to transfer Bob 6.5 bitcoin. Choose the component and let me know how would you proceed. Just thinking about your physical money which component you will choose. Ultimately this program has to be done by the this uh this conversion or the selection has to be done programmatically but as of now we are considering it so we are solving it. So which component or which combination should be chosen? 5 + 2 others also see 5 + 2 or anything else I should try which component we should choose 5 + 2 5 + 2 correct. Now you see if we go with this 5 + 2. So what we are transferring to this five bitcoin plus 2 bitcoin and once this transaction has been made. Now you see these two components are reserved. These two components are reserved. Once the transaction is verified how much change will be coming to the Alice? Once the transaction is verified, how much change will be coming to the Alice? How much change will be coming to the Alice? 0.5 0.5. So we can say that this is my UTXO unspent transaction output. This will be 0.5 bitcoin. So what will be the updated balance of Alice and Bob? Calculate the balance. What will be the updated balance of Alice and Bob? So you see Alice was having what? 10. So we transferred 6.5. So balance should be 3.5 bitcoin. What about Bob? How much will be the balance? What about Bob? So 5 + 6.5 is 11 uh this was 11.5 11.5 bitcoin. And if I talk about the components now, if I talk about the components earlier it was available. So can I say that this is being replaced by 0.5 bitcoin. And what has been achieved from this? This is 5 bitcoin plus 1.5 bitcoin. Is it happened like this? Is it happen like this? Check check my component theory. Is it correct or should we change something over there? See what happened into this case. This I was transferring I was transferring what I have taken one component from this. Okay. Transferred two bitcoin transferred but we have got a change also that change is what 0.5 bitcoin. So one bitcoin remaining same two bitcoin remaining same. There this person has got what? three bitcoin plus 2 bitcoin and then I have 5 bitcoin plus 1.5 bitcoin so this way we are g giving up here does bob return 0.5 uh Sanjie in this case so whenever we say the component is designing so program is able to convert that two bitcoin to 1.5 bitcoin so now you see in actually whatever we are talking do we have any physical currency Do we have any physical currency? No, we we are not having any physical currency. Everything is according to a program now. But how this Bitcoin is making it short? They have used Bitcoin scripts to manage the component over there. And what is the reason of this complication? It could have done like a normal subtraction also. It could have done with a normal subtraction also. So they wanted to make sure there is no double spending problem. Now what is double spending problem? What is double spending problems? So we know that in Bitcoin average time for block confirmation is what? How many minutes? How many minutes? 10 minutes. So in that 10 minutes you see let's say now my when my account will be updated this 10 bitcoin when my 10 bitcoin will be updated right now my balance is 10 bitcoin when this will be updated can I say that after the block confirmation can I say that after block confirmation yes after 10 minutes. So meanwhile if I am using my all the balance and I might use something like a double spending problem also in actual I have already spent five bitcoin again I'm trying to you know change that and that logic is just checking my balance over there by arranging into the component. So they are trying to solve the problem of double spending and that is why they are using what UTXO model. Let me explain again here. So why what we are doing? So basically UTX is the equivalent to digital form of change. Correctum correct. Yes. This is the correct thing and very well spoken about this. So you see here what I'm trying to say. We have taken example that we have two user. One is Alice, one is Bob. Alice initially having balance of 10 bitcoin. Bob is having five bitcoin. So this time we are not having the total account balance like this. The whatever is the balance this is being arranged into some partitions some components and it could be anything and how it is different from you know physical money like in physical money we have certain type of modes like only 500 only 100 only 200. So in this this is not like that. So there are programs where they are working into the same scenario to generate the components. Whatever is the component it is coming to the users. Now we have taken that Ellis is willing to transfer 6.5 bitcoin. So what we have chosen from this five bitcoin and 2 bitcoin and this is being sent to Bob. their program is working and this program is making sure that 0.5 bitcoin is returned as a new component for the Alice. So that is why the balance is being updated as 3.5 bitcoin and 11.5 bitcoin and ultimately we do have such arrangement over there. Okay. Uh where is these components are stored? This will be stored into my wallet only. So let's say I created my account on the binance and this is my wallet. So it will be stored into the same place. How the initial components are decided say for Alice uh 10 bitcoin breaking it to various denominations. Rajes so whenever u I got this denominations or whenever I received it so it was through the same let's say somebody transferred me 10 bitcoin as you are taking into the example. So this component is coming to me into some kind of form. So that form is directly coming to me. So whatever was the denomination that is coming to me. Another case you see when the minting is happening the bitcoin is minted. So that time the component is 3.125. That time the component is 3.125. Let's say I transfer to somebody else. So maybe I'm transferring this from this. I'm transferring 1 to5. From this I'm transferring 0.125 bitcoin. So what is the next component for me? What is the next component for me? Three bitcoin. Can I say that? Can I say that the next component is three bitcoin for me? Correct. Correct. Now let's see more examples there. More examples because we need to understand like this. Let's say Alice is new to the Bitcoin community. Okay, that time she purchased from somewhere and when she is purchasing that time again the component has to be come through whatever is the community giving. So let's say she just p say p p p p p p p p p p p p p p p p p p p ppurch purchase one bitcoin as of now. Next time her friend is transferring her 2.3 bitcoin. So this way the component will be arranged. Now when she is transferring somebody, let's say she wants to transfer approximately three bitcoin. She wants to transfer approximately three bitcoin. So she will be left with what? She is using one bitcoin component as well. 2.3 bitcoin component as well. What she is transferring three bitcoin. What will be the balance for her? What will be the balance for her? 0.3 0.3. So can I say that a new component is generated for her? Can I say that a new component is generated for her? Uh V. So all the components have UTXO label with them in wallet. Correct V. Correct. Correct. Do you understand the UTXO model? Now all of you very simple concept. U now give your thoughts on to this. So what is logic? Because transactions also can be traded. So it is based on single transaction denomination. For example, if I bought one bitcoin, 0.5 bitcoin, 0.25 pair. So three denominations for me. Correct. Rajes. Correct. So don't you think they're increasing the complexity into the system? Don't you think Bitcoin is increasing complexity into the system? And uh the reason behind is that because the time period that we are considering that is very very high 10 minutes is very high time. So that is that is only you know one uh one thing we we can say that this is making them efficient for uh double spending problem. Okay. Uh so what is logic? Because fractions also can be traded or it is based on single transaction denomination. Uh Rajes can you please unmute yourself? I think it is better we interact then we can understand this. >> So >> hello >> so I'm just saying that uh this is for the example which you have taken five uh 532 just an example correct >> but these transactions are happening. So denominations are not fixed. So idea is not about the replica of real money transactions of fixed denominations. >> So this is basically whatever you're transacting because it's in fractions also right you can buy 0.05. >> Yes. >> Just how many transactions are the denominations right? >> Correct. Correct. So this changes or UTX or whatever we are considering this only happens at the time of when say the change is coming. So that time they have not kept it. Okay. uh like physical money we are fixing some kind of amount. This is not required into this case and they're just trying to solve one problem that is our uh what we can say double spending problem and only the reason they are taking it because their uh their block confirmation time is very high. So this is one of them they have taken many step this is one step into a part of the same double spending problem. Uh Ashwin so when I have to get the total balance for a person do we need to add uh okay uh Ashwin this is not our responsibility so wallet will be automatically doing it is showing me the total balance only but when I see that I can see all that you know fractions as well so it will be automatically calculating for me uh Rajes do you want me to unmute if you're left with something. Okay. Okay. Thank you. Uh Ashwin, you got the clarity onto this. See, in case you have any question uh anything you you have some doubt, it is better to discuss rather than sitting like that only then we can understand that what is uh what is the level of understanding of for each other. Yes. Yes. Ashwin we can we can take a one more example for this see what is double spending problem let's say this is I'm having 10 bitcoin or I take less amount here okay so I take five bitcoin so this is Alice so we know that block confirmation happens only after 10 minutes okay so what I did I transferred five bitcoin once I transferred five bitcoin One more time I transferred one more time. This is five bitcoin. Okay. Now you see I have only five. But what I'm trying to do here, what I'm trying to do here, how how much transfer I'm trying to do? Can I say that 15 bitcoin? And you will be asking how it is possible. It is possible. My account is still not updated. I just created the transaction. I submitted it to the unconfirmed transaction pool and now it is still with the uh waiting for the verification. This is with the minor or this is you know sitting or this is into the unconfirmed pool. But what I tried here obviously it will be stopped at the minor overight but you are increasing what you're just increasing the complexity into the system. So Alice tried to transfer how many times? Three times with the what total amount causing a 15 bitcoin. Now if I say this component that it is entirely being freezed. This component is entirely being freezed. So this freezing is giving the power that this cannot be reused. Okay. Now I take one more example. Let's say Alice is having one more bitcoin. Alice has having one more bitcoin. Now she did what? She tried what? She tried what? this particular bitcoin to transfer at one side. Now if we follow the utxo model this has been reserved. Reserved means I cannot use the component. But can I use this component? According to the utxo model, can I use this component? Yes, I can use it. I can use it. So when I'm using this, this again become reserved over there. So now you see these two components are into the reserved side. So when it is into the reserved side, I cannot do the double spending. I cannot create the fake transactions here. I cannot create the wrong transaction here. So that is why the double spending problem is solved at a certain level. Another case you see another case you see uh let's take one more example. In this case what is happening here? This is case of what? 1 bitcoin, five bitcoin, 1 bitcoin and two bitcoin. Now in this case I just want to transfer what? One is five bitcoin. Then I want to transfer one bitcoin and then I want to transfer 0.5 bitcoin. See this this very carefully. I I want to show one more thing here. And then I want to do 1.5 bitcoin. Okay. This I want to transfer. So this is my let's say this is my transaction one. This is my transaction two. This is my transaction three. This is my transaction four. Okay. The sequence I'm also following up. Will it be okay? Can I do that? Five bitcoin according to the UTXO model. Can I do that? Five bitcoin. Five bitcoin. Can I do that? Yes, I can do that. One Bitcoin, I can do that. Two Bitcoin. This is for what? 0.5 Bitcoin. So now tell me, can I make the transaction four? Can I make the transaction four? No. Can I make the transaction four? No. I still have my account. I still have my amount. See, five Bitcoin reserved. One Bitcoin reserved. Now you see two bitcoin is also reserved here. Two bitcoin is also reserved here. I need to wait for next 10 minute once I get my change then I can do the 1.5 bitcoin. Right? Have you understood this or I should explain this uh again. I'll come back to the questions everyone. I'll come back to the questions. Have you understood this? See what what we are trying uh trying to say here. I have some amount. Okay, it is solving my double spending problem also. But sometimes it may happen that I still have the amount just because my transaction is not verified still I cannot use it. So that is also a possibility here. Uh yes see what we considered here uh Manisha that we have component like five bitcoin, one bitcoin and two bitcoin that is making my total as 5 + 1 6 + 2 is 8 bitcoin. Okay. Now what kind of transaction I want to do? So in transaction one I want to transfer to Ram. Transaction two I want to transfer to let's say Sham. Transaction three I want to transfer to Bob. This I want to transfer to U some XY Z guy. Okay. So now in this case you see this is my transaction one. Second one. Transaction two. Transaction three. transaction four total amount which I'm trying to transfer this is 5 + 1 is 6 6.5 and total the same amount I want to transfer I want to you know uh nullify my balance now in this case you see I made transaction one this component reserved I cannot reuse it I transferred one bitcoin this component become reserved I cannot reuse it again I made transaction. This is transaction three. In this case, I was trying to transfer what? 0.5 bitcoin. I'm only left with what? 2 bitcoin. So now this is also reserved. I have next transaction. So this is transaction of 1.5. Logically I have the balance. But if you follow the UTXO model, my all components has been become reserved. So when it is reserved, this two bitcoin has been reserved. I cannot reuse it unless the block confirmation happen. When the block confirmation happen for this transaction three, what I will receive? I will receive a UTXO. That UTXO will be of 0 or in fact 1.5 bitcoin. Once I receive this component, then I can make this transaction. Correct? Uh Manisha, do you understand this now? Uh Malaysia, do you understand this now? Okay, now let me come back to the questions. How is it flagged as reserved when the block has not been updated till 10 minutes? Ashwin see whenever I use it, this is being flagged. Whenever I'm using it, it it becomes flagged at that same time. uh Jaggerat what Alice has 20 bitcoin but she transferred three times five bitcoin into three times so in that case uh jagernad this also depends on the component if component is trying is component is having the same thing that is okay if component is allowing the same thing that is okay so with this theory say I have two component five and five total 10 I put a transaction of 7.5 bitcoin and then I want to transact 2.5 I can't do the second or as both component is locked correct correct Rajes so I was explaining this only and you have rightly said this and then do we have any kind of bitcoin denominations jaganit uh nothing is fixed so program can make any kind of denomination so it's not having any fixed amount if the double spending concept would not be there then a person with one bitcoin would be able to carry about infinite transaction. Correct answer. Correct. So once we start the transaction then our wallet freeze bitcoin which are used for transaction. Uh correct V. Okay. UTXO is received after confirmation of block. Why cannot it happen immediately at exchange? Sanjie it see in the transaction we are just waiting for the same purpose only. And we are not making the block transaction wise. We are making the block as a collection of the transaction. So my block is not carrying one transaction. It is carrying multiple transaction and we are talking about the distributed ledger. So whatever we do have this is into into we can say that this is into collectively with every every node. Okay. uh like let's say if she uh like let's say he she made a transaction of one bitcoin but as the double spending concept is not there so he will be able to transact that one bitcoin again because it is not deducted from his wallet see these scripts are what these are actually governing that all kind of UTX and everything so for every transaction automatically programming is there which is being managed or which is managing that how uh the transfer will happen how the transaction will happen, how the UTXO will will be converted. So, automatically is embedded over there. So, as a user, you do not need to do anything for you. It is a normal graphical user interface. You just put your amount, click on send, uh put your uh senders address and everything. But by default, this is attached to the transaction and this is taking care of everything. Uh witness is something here we divide it. See this is we can say that public key script witnesses the balance of that script. So you can say that this is hash of all the transaction that has happened. So you can more consider it as a hash value for the uh the script that is being executed over there. So there is one more concept Rajes that is segated witness segit. So I'll explain that that time you'll get more understanding of this. So to understand this we'll cover segwit. So segwit is actually related to uh we can say data compression. So I'll explain this as well. Earlier it will it was not there but now the bitcoin has revised their uh scripts and they're including here witness and this is part of segwit which is more related to the data compression technique. But I'll explain this because because before understanding this segwit we need to understand one more concept. uh who is considered to be sender of UTXO amount. So this ashwin in this case the sender will be the transaction. Sender will be the transaction. So actually you know it recently happened not recently I'll say last year now we are into 2025. If I show you that that amount was you know very very high at that time. See uh so we are talking about 21st July they have given the explanation and we can see how much of the asset so this is news of Hindu you see vazer crypto exchange hack how much of the asset was lost and what happened next so lost over 230 million in a security exploit 230 million is a very very big amount after one of its wallet was targeted on 18th July and has decided to socialize its losses in what uh unorthodox damage. So why I'm talking about this? So since beginning we have seen that blockchain came into the picture because of the security and transparent transparency we say that we we will not have any any kind of hacking or anything but this is also possible here. So now one of the attack if I say do you think there is a possibility of the 51% attack on the bitcoin do you think there is a possibility of 51% attack logically you tell me is it possible or not logically probability is always there correct probability is always there so now what is 51% attack so we say that u when a minor propose a block that has to be evaluated by the rest of the miners. But now I'm saying that my 51% nodes into the system are corrupted. So can I say that my entire blockchain is a failure in that case? Can I say that my entire blockchain is a failure in in that case? Can I say that? So yes. Yes. But if we see uh theoretically it is possible, theoretically it is possible. But when we see that if somebody is actually trying to do that they need a lot more resources especially with the Ethereum. Especially with the Ethereum you see they need to buy all the ethers and everything. So uh in this case this becomes very difficult but this is also one of the attack and it might be possible somebody is taking over that that blockchain as well. So this is one of the type of attack. Another case I say here. Another case I say here mining pool. We all remember. Do we all remember what is mining pool? Mining pool. Can I say that group of miners working together? Can I say group of miners working together? So in that case you see group of miners they're working together. Now let's say uh I I speak about that. So there was a time when China was the was having the highest mining pool. There was a time because now recently China has you know uh uh made it illegal to do the mining into their country. So now this this all mining pools has been shifted from China to the US. So now in this case you see geographically geographically can I say that we know the location of miners. Can I say that geographically we know the location of minors? Obviously I do not know the exact location but any any how we have a certain idea said that these miners are linked to one particular country one particular country. So what I'm trying to say here from majorly miners were running through China but now this has been shifted to US. Okay. Now is there any possibility? So one we are just you know probabilities we are considering is there any possibility that internet or the ISP working into the US that can be hacked probability you tell me internet service provider we understand ISP of US can that that be hacked is there any possibility probability yes probability is there but if you see US is having a very good security in terms of cyber security into the information security. So if we technically we talk about it is very difficult theoretically we say it is possible uh Jaganut ISP is internet service provider internet service provider so like we have the Tata and Jio here so which is which is providing us the internet services. So these are the ISP. So in this case you see we're talking about the throughout connection which which could be possible. So let me just give you more examples for this. Uh one of the attack is fishing attack. So fishing attack is what? Fishing attack is what? Have you received some kind of u lottery message? Have you received some kind of let's say uh your loan has been processed? you click on this link to get the further information. So all of us we receive this kind of you know messages. Similarly emails are also there. Emails are also there and uh even you might have received uh today what is what is going on. You receive a call from a couer kind of a guy and uh he will mention that you would your couer is there and if you need to return this or something you need to press that and uh do this. So these kind of things we see very normally. So what is fishing? Fishing is basically sending unauthorized links to someone. So that when they click on it actually your amount or you will get the financial loss. So in this case you see sometimes what happened let's say I do have uh I take example Exodus. Exodus comes in which category of wallet? Exodus comes in which category of wallet? Web, mobile or software? Which category? Which category? Both. Correct. That is that is also right. So this uh I assume that this I do have with the web based wallet or I do have some kind of mobile application. Now somebody sent me what? A link. a link on the same or I can say that a unauthorized link. So this is onto my WhatsApp and because of this unauthorized link what happened over there I actually clicked on that link and now this is making a automatic payment. This is making a payment from my mobile wallet to that account. So this is you see this could be done with the fishing site. This could be done with the fishing site. So there is a possibility that I have all these kind of a wallets and somebody is trying to intercept me. They will be sending me unauthorized link. If I click on the same link I will be thinking that there is nothing is happening but on the background my applications is being used and the amount is being transferred. So uh now another question if from my account I saw that uh some cryptocurrency is being transferred to a wrong address. Some cryptocurrency is being transferred to a wrong address. So can I get it back? Can I get it back? Can I complain it to someone? Is there any possibility like that? Something wrong happened. I by my mistake or by fishing there is a address where the transaction has been done. So can I get back that money? No, you cannot get back that money. So that is entirely not possible into the cryptocurrency system and even we do not have any any kind of you know uh compli uh regulatory framework as well where we can complain or something in our uh I'll say let's say in India we have the RBI to complain over there even if you see when you have some ATM card or something it has been lost so you can complain and you can immediately you know shut it down. These possibilities are there but nothing exists with the case of what the cryptocurrency. So that is why fishing is a very dangerous one into the case of Bitcoin. Okay. Now you see uh there is a civil attack also. This is very interesting one. This is very interesting one. So the cy attack listen this very carefully. So we all know the 51% logic. Do we all know the 51% logic? Now I am giving two statements. Correct me or give me your understanding onto this. So I'm giving two logic. One the one logic is that if my notes are honest 51% will be achieved soon. If my nodes are dishonest, 51% can be achieved with some delay. With some delay, think about it and then let me know. Two logics I have given. One, if my notes are honest, honest means whatever is the right or wrong, they're taking the decision and accordingly giving the verification. Let's say uh these nodes are having a proposed block. So what is what do I mean by the honest and dishonest node? So this is let's say this is a honest node. So this honest node will be giving the right decision. So if the proposed block is correct so it will be taking as correct. Dishonest node will be giving a wrong decision. Wrong decision is what? So in this case this node already computed that proposed block is correct but still it is saying it incorrect. Okay. So in this case now you read the read the statement. Now you read the statements. So now what is happening with this cyble attack symbol attack is we can say that a smaller version of 51%. A very smaller version. So now let's say there is a Bitcoin community and they have a competitor. The competitor is let's say XY Z. Now they want to they want to run their business and they want to disturb the Bitcoin's business. So what they did they created a civil attack. So civil attack is having dishonest nodes into the system. So they are not becoming minor for their reason. What they are becoming minor whenever they have come across the proposed block they will be voting as wrong way. They will be root vote voting into the wrong way only. So when they are doing it so ultimately they are getting delay to achieve the 51% attack. So in that case what will happen this 51% attack let's say it has to be achieved at 1010 now it might be go to the 1030 so I'm just taking a example for this or maybe 1020 so they are causing delay into the transaction or we can say the block confirmation uh no this is not to steal the bitcoin this is just to delay the see if the uh now you see if we have the average time of block confirmation of 10 minutes. We are still okay with that. But if it if it increases to 1 hour. So can we say that can we say that trading market will hit cryptocurrency trading market will hit. If that time becomes 1 hour it will obviously it will be it will be a hit. So there is a possibility that the other competitors they're not trying to steal anything. They're just having what? They're just having some malicious node into the system. These nodes just trying to disturb the working of other nodes. So that is the case of civil attack. So civil attack if I just brief it, this is creation of dishonest node into the system and these dishonest node will be doing the task into the wrong manner. But anyhow they cannot take the wrong decision because to take the wrong decision all the dishonest node should be 51%. And that is very high to achieve. So they cannot achieve it and smaller what they can do they can do the civil attack. How they achieve it to delay block confirmation. Correct. Uh when you think of I have a network let's say I try to dry draw it into paint. See, so let's say this is minor. This minor has already win the game and he is broadcasting the network network with the proposed block. This is one. This is one. This is one. This is one. This is one. This is so these all are nodes here. So I'm not taking 100 nodes now. I'm taking just few nodes. Now you see in this case let's say how we are moving geographically. It is getting the proposed block. It is sent to this. So this is also dishonest. It is sent to this dishonest. This is also dishonest. This is also dishonest. So in case it was not dishonest in case it was not dishonest. So by this time by this time it might have achieved the 51% thing. By this time it might have reach achieved the 51 percentile but now it has to wait to go through this also go through this also go through this also and only in the end ultimately it is having what it is having the right answer. So as of now you see the if we at this time if we see the quantity will remain same only quantity will remain same means the voting is 50% or whatever voting I'm talking about. So correct and incorrect voting that is entirely similar. So that is why we had having to say that delay is introduced here. One more case you see that broadcasting is happening and it will take time to reach from pier A2 or pier 1 to pier 10 in between whatever peer I am receiving that are dishonest. So as of now I cannot make any decision by that time because ultimately what we want we want 51%. So we are still waiting to get the confirmation from others right uh Vinnie I hope you understood this okay so I just delete this. So now we have seen the civil attack as well. Uh fishing you already understood. See in the fishing how many things could be used? So chat fishing, message fishing, email fishing, social media fishing, Google adword fishing. So all those could be medium for this. What is message fishing? What is m message fishing? Can I say my text message? The medium is my text message. the which we are receiving on the phone email we all understand social media so now you see on the Instagram also we are getting you know these kind of messages so Google adword is also one of the example so yes we do have multiple links sent through the message correct correct so normal text message when it is coming through the email this is this is your uh the links are coming to from the email over okay now I come to the rooting ing attacks. So now what is the rooting attack? So this is basically targeted to the no now you see this is not being targeted to a user or something. This is onto the network. Now in the network you see this is what BGP router. Now BGP stands for border gateway protocol. This stands for border gateway protocol. And now in this case you see we are actually having uh when I'll just come to this border gateway protocol. Now in this case you see this is based on what this is trying to give the directions to the packet. So when it is trying to give the directions to the packet let's say this is being hacked. Can I say that packet will be going to a wrong direction? Packet will be going to a wrong direction. Can I say that if this particular router is being hacked, that router's responsibility was just to give the direction like where it should transfer to the next. Now this is doing a wrong task. So in this case you see this is also one of the type of attack where rather than targeting a particular scenario the router or these kind of a devices are being hacked by the hackers and this this can be maliciously maliciously send this packet to some other location so this is not only with the blockchain this could happen with any type of data this is not only with the blockchain okay uh V I'm coming to your question once validator validates block then only He send it to peer node to validate it. Uh correct Vinnie. So maybe you wanted to say minor validates the block then only he sent it to the peer node to validate it. So it is just like a proposed block. So all other miners need to revalidate it to get the 51% voting. Okay. Uh this also I I believe we have already discussed what is full node to become minor. What you need to become? Full node or light node? To become minor? What you need to become? Full node or minor? Full node. Full node. Full node is downloading the entire blockchain. Uh Rajes, this PPT is available on your uh portal, but I'll show you where it is available. Okay. Full node. Full node. Okay. What what is light node? Who is light node then? Who is light node? Viewers. So can I say that if I am on the uh blockchain explorer, I am I am working as uh light node. I'm on the blockchain explorer and can I say that I am a light node. So yes, I'm on the light node. Now you see uh one more thing we see here. Let's say I want to join the network. I want to become the miner. What I want to become? I want to become full node. So full node. So we have seen a website. We'll visit the uh bitcoin website. What we will do? We will download the bitcoin software. Now when we are downloading the Bitcoin software, the server will be connecting me to a node. The server will be connecting to me a node. Now you see I requested a C node. C node is providing me all the addresses. See now what are the address we talked about that this is tier to tier network. So I should have if I am becoming a minor I should have addresses of all other peers. I should have addresses of all other peers. Okay. So but who will be providing me all those addresses? How I will be connected? I'm saying that I want to become a part of peer-to-peer network. So we will when I'm downloading the bitcoin I will be linked to a seed node. So seed node will be providing me address list of all the peers so that I can form a connection with those peers as well. So every time a new node or a new minor joins the network the same process happens. So requesting the C node, retrieving the address list, selecting the peer node and updating updating the network. Now why I'm saying updated the updating the network. So let's say I have 101 peers. Now one more is added. So there is one more connection. So 101 + 1 that is equal to 102 peers. Now can I say that recent peer will be also added also added in the also added in the address list. Can I say that recent peer will be also added in the list. Can I say that? Yes, it has to be added because it is just what address list over there. Ash I'll come to your question just give me a second. Uh now in this case you see the same process we are following up here. So seed node connected with this node give me the address list. By this address list it is getting connected to all other list as well. So this is making a updated copy into the network mining we all understand. Now let me come to the Ashwin's question. uh when a block when then when then a block is broadcasted to a node does it forward to another node only after it has completed completed validating the node no Ashwin it is into the process so let's say I received a block I'm working on that and meanwhile it is being transferred to others as well because for my verification also it takes time so it is not wasting into that broadcasting is sending to everyone So what whatever I have I'll update with my answer correct or incorrect. So that I'll update to the bitcoin. Okay. Now we'll come to the orphan block. This is also left. Do we have facility to select our peer nodes? uh when it is automatically selected but if you need to select the immediate peer that you can you can select the immediate peer. So one term is immediate peer. Immediate peer is that is closest to your your connection. So that you can choose but uh see you will not be knowing the exact thing over there. Everything is encrypted. So you're not knowing IP address or something. You're know not knowing that okay this person is belong to which city or which country but it is showing you the nearby route. Every information is encrypted. Okay, next concept is orphan block. Uh, can I move to this? Next concept is orphan block. Can I move to this? Okay, now you see now you see in this case uh this is the concept which we left when we started with the proof of work. The question was what if more than one minor solves the puzzle at same time. Okay. So one case we asked is it possible? So the answer is yes it is possible. So what will happen in that case? So initially it is very difficult for Bitcoin to recognize this. So what happened into that case? Now you think of a case that I have minor A and minor B. So these miners solved the puzzle. Let's say uh nons. He also received the nons. He also got the nons. So both of them created their block. So they started they are not aware about the things here. The broadcasting has been started. What is broadcasting? What is broadcasting? Now, now you should understand this. What is broadcasting? Can I say that? Sending the proposed block to the multiple one. Can I say that sending the proposed block to the multiple peers forwarding to another node? Yes. So, broadcasting is what? Uh let me write it here as well. So, for your later understanding. So I'm writing here broadcasting is broadcasting is sending proposed block to all peers. Okay. Block to all peers. All right. Now this is also doing the broadcasting. This is also doing the broadcasting. Now there is problem. Now how many miners are doing it? two minors currently if you see you can add you can work on only adding up one block. So there is a function we can say or a programmically with the help of program there is a function call we say function call that is known as synchronization call we call it sync call. So that happens in the blockchain with all the peers and what it checks it checks the it checks the all blockchain peers or all peers all peers are having the same state of the blockchain or not. Peers having the same state of blockchain or not. Okay. So when it is recognizing so it got what it got let's say minor A is adding block X minor B is adding block Y. Now in this case they found out they find out the sync call the sync call that is a program that find out that block block x block x which is related to minor a block x is having introduced into 50 peers. block Y is there into 30 pairs. Okay. So now you see two different blocks are being floated into the blockchain. One is block X, one is block Y. Block X is through minor A. Block Y is through minor B. Reason was there that they solved the nons at the same time. But it has been recognized with the sync call only. So sync call is being done after a fixed amount of time. Okay, now you see they need to choose one. Which one is easy to delete or which one is easy to discard? What should I discard? 50 pier or 30 pier? What should I discard? 50 pier or 30 pier? Which is better to discard? Which is better to discard? 30 pier. 30 pier. So now which block is this one? Which block is this one? Block Y. Block Y is associated to which minor? minor B. So I say here block Y while will be discarded by the synchronization call and this is known as orphan block now. Okay. So now you see this is being discarded. So these all 30 tiers will be also updated by block X whenever the time comes. Meanwhile, all those transactions which were part of orphan black block, listen this carefully. Let's say I have total 1,000 transactions that were part of orphan block. Now they all will be transferred to the unconfirmed transaction pool. they all will be transferred to the unconfirmed transaction pool. So now you see in this case what is happening in this case this example you see can you see here block 3 A and block 3 B can you see here block 3 A and 3B so this is being discarded and it is known as orphan block so this being sent to back to the unconfirmed transaction so that the same state remain with the blockchain okay I hope now you understand this concept what is the orphan block so what will be to answer if you you want to give in two lines. What is orphan block? What is orphan block? But how you can define this discarded block? Yes, discarded block. Correct. So in case you see if uh three miners are doing at the same time so same thing happen will that only one will be chosen as the final block. Correct. Uh now proof of stake is having the pro orphan block or not. Proof of stake is having the orphan block or not? No they are not having. It is not having. And also let me tell you one thing uh earlier Ethereum was Ethereum 1.2 1.0 Ethereum 1.0 was using proof of work. That time orphan block was known as uncle block in the Ethereum. See in the bitcoin the name is always same in the bitcoin this name was always orphan block but in the block uh ethereum 1.0 it was known as uncle block but now if you see now if you see ethereum 2.0 O that is following a proof of stake. So it is not having I'll say no uncle block here. So I'll not say no orphan block. I'll say no uncle block here. Okay. Will time to get 51% approal will be higher in this case. Uh yes Rajes. This time it will be higher. This time it will be higher because two two blocks were floating over there and then synchronization call was there was there. So uh the discussion has also happened. So it can take more time. So that is why you see the time that is 10 minutes given that is only average time. It's not always fixed. You'll get 10 minutes only. It can be more than that also. It can be less than that as well. So it depends on the runtime conditions. Okay. Do we all got the clarity of the orphan block and uncle block? Have we got the clarity of orphan block and uncle block? Any question as of now? Uh what if when block y also have 50 ps at the same time shamu that time it will be choosing randomly one of them will be chosen randomly and uh it's good part you have asked this question so that time it will be choosing randomly changing the complete consensus algo of a crypto is just like remaking the crypto itself or it needs only some modification due to which the complete consensus Algo exchange talking about Ethereum uh and assuming in that case they do the forking forking means that let's say u what happens obviously the previous things we cannot change it so I assume that till Ethereum 1.0 two they have 1,000 blocks and after this this is 1,001. So whatever they are doing they are changing with this block not with the previous block. Whatever they are doing that they are changing with 1,001 block. So whatever policies they have they're implementing into the current but the older version they are not uh I'll say changing or something. So this is like shifting from one protocol or one consensus algorithm to other soft fingish. So I do have some questions uh with you. How is bitcoin address generated? How is bitcoin address is generated? I have four options. Hash of public key, hash of private key, hash of the person's name, hash of any random value. So correct hash of public key. So this is hash of public key. Bitcoin address is always generated with the hash of public key. Okay. Uh what does a Bitcoin block header consist of? So you read it carefully. What does a block Bitcoin block header consist of? So as of now I am getting A as answer one. So let me show you the A is correct one. A is correct one. See version previous block hash ML root timestamp difficulty and nons. See this is carrying nons as well. So it's like it is carrying uh major majorly all the options. So that is why A is chosen here not C or any another answer ashwin difficulty is that that is having some values what will or how the nons will be solved. So this is based on that when I say that difficulty so difficulty doesn't mean that it will be decided on the basis okay make it complex or make it increase or decrease so it is having a value on based of that nons is calculated so it will be let's say I have a number uh I say 0 0 this this this is this and one I say that difficulty This is x x. Which is which which one you think which is more complex to solve? Which one you think is more complex to solve? If we talk about some puzzles or something. So this is all about the digits. This is all about the digits. So this is this kind of difficulty level we uh achieve into the case of bitcoin. Uh, how frequently is the block mining reward? Reward is half. I think this you will give me the correct answer. It should be having the correct answer with everyone. B. Yes. The last halfing happened on this. I'm asking you when was the last time the halfing happened? April 24. April 24. Okay. Which of the following statements is true in the context of Bitcoin? Which of the following statement is true in the context of Bitcoin? minus must solve a mathematical puzzle to generate a block with leading zeros. Correct? Correct. All of you are correct. Let me show you this thing. Atomic wallet. Okay. So this is also you know one of the wallet here. So uh this PDF I'll share with you all. First you read the statement and then I'll take you to the document. So whenever you get the time uh you can try this. So you are a blockchain expert and have been asked to download and set up the atomic wallet to conduct a transaction of bitcoins. Uh just a second I think my screen is not visible. Okay. Yes. To download the configure the atomic software or wallet. Create a new auto atomic wallet. Explore a transaction of bitcoins and other currency using the atomic wallet. I think same kind of task I have given to the exodus as well. So you just can go through it. So this is the website atomicwallet.io. You can download it. And you see this is available into multiple oper uh operating system Windows, Mac OS, Ubuntu, Debian and Fedora. Similarly onto the applications as well. So this screenshot is for the uh Ubuntu machine. So in uh in our case it will be very simple into the case of Windows. So you do not need to follow all those steps if you are onto the Windows machine. But in case you are on to the case of I'll say uh Ubuntu platform. So you'll be following the same path and once you have it so you can create a new wallet. You can provide the password. This is like a sign up process. Once you provide the password, you will open the wallet there and you'll be able to see you remember in the Exodus also we were seeing the same kind of thing bitcoin all other cryptocurrencies and everything. So explore a transaction of bitcoins and other currency using atomic wallet so that you can do some conversion. So here you see in the screenshot 200 USD has been converted to bitcoin. Similarly the Indian currency as well. Then click on swap from the left panel. Swap is what? Changing from one currency to another currency. So this we are trying with the 10 ether to the bitcoin over there. So this price might be have increased this time. So after this you need to go through the NFT gallery. NFT is your nonf fungeible token gallery. There you can see something related to the how to buy a NFT. So transaction can only occur if there are enough bitcoin. So just a exploration. So one one of the you know uh one of the another wallet you can try. So this uh entire PDF I'm sharing and plus link as well. So in case you want to try it right now that also you can do. Let me give this link. uh Ashwin the swapping works with the uh current price of the market. So whatever is the current price I will be getting the equal equality to that and these exchanges are responsible to perform that task. Yeah in case of blockchain so these exchanges are working for me. So every every cryptocurrency can be converted to other cryptocurrency. So market price is already set for the same. Uh Anumuan we do not need to download the Ubuntu or anything. We do have labs with us. So actually when we are working with the Hyperledger fabric that is only workable into the Ubuntu. So we are having lab machines those lab machines can be used for the same purpose. We do not need to do any kind of installation or something. So we will be uh going to our portal and then we will see in the lab uh shy it is almost same only it is almost same only just it is your choice like which which particular wallet you want to choose and let me show you this thing as well because uh might be some people are not aware of the pities and everything and I'll show you the labs also just a So you have your all LMS there and I'm logging into my portal. So as of now what do we know about the Ethereum blockchain? So this Ethereum blockchain is also coming into the category of what we can say public blockchain. But how it is different from the Bitcoin. So we do have two three differences we can easily see. The one is it is right now working on proof of state. This is having only transaction fee as reward money. It is also giving us opportunity to what we can say this opportunity for the creation of programs. So that programs are known as smart contract. Smart contract. Maybe you have heard this term multiple times into into the blockchain word. So we we can make we can make the contracts over there smart contracts there report money. Okay. And also now you can see this is something combination of cryptocurrency plus smart contract. So I'm writing SC for the smart contract. Also when we talk about that the community is known. Community is known means so this is not like a anonymous one. So we do have very renowned uh I can say stakeholders into the Ethereum community. So this community is known. So I can say that by default trust is also there. Okay. And uh can I say that this is second highest cryptocurrency right now in the market Ethereum can I say that it is second highest cryptocurrency into the market. So yes this is also one of the fact and uh they have achieved it very soon as in comparison to the other cryptocurrencies because of the concept of the smart contract. Then in uh in the next case you see one more thing we see the Ethereum also give me the support for creation of NFT or even I say FT FT stands for fungeible token and non-f fungeible token. So we we are able to create these two as well by the help of the smart contracts as. So these are some some uh things that we already already understand with this and with the help of proof of stake we know that there is nothing like no uncle block and in this case uh no parallel parallel block creation will happen creation will happen. So these all things we are already aware about. Okay. Now in the same case you see is it payment cryptocurrency or only utility based token currency. Uh if you are Rajes if you're talking about payment as in payment cryptocurrency yes we can make it both both the way we can have it. So ether can also be done uh non-f fungeible tokens can also be done. So both are possible here. All right. So now we know that uh what is the cryptocurrency for Ethereum? This is ether. So have you heard about EA? Have you heard about EA? Maybe not. So this is actually enterprise Ethereum alliance. So this is a community. Now what kind of community? What kind of community? See I we know that Bitcoin is having very high price but on the back of our mind it is also there that we still not aware who is the owner. Uh what we we are still afraid one day they will come and they'll close everything. But these kind of assumptions are always there. Now when I say Ethereum so I go with this same thing. This is the term that we are using enterprise enterprise Ethereum alliance. Yes, this I'm looking for. Now you see what is this term. So I'm just sharing this link also. culture. In this case, you see how many members we have and what kind of member we are seeing. Okay. So, now you see what names you can see. Microsoft, Sendender, Ranger Fish, uh Ara Capital, Block App, Consensius, this is also one of the company, Ethereum Foundation obviously and EY, uh I I believe all of the name you have already heard of. So now you see these all are part of this alliance enterprise Ethereum alliance. So when I say whenever they are taking a decision in that decision these all members are part of this these all members are part of this can I say that because of these big names I do have more trust now into the community because of these big names can I say that I do have more trust into the community can I say that so yes now it's like that if we compare it from the Bitcoin and if we compare it from the Ethereum So we we come up u we come up that okay the now I I have some kind of reluctant things onto the bitcoin we I know the prices are very high but what is the future we are still unsure but when I come to the ethereum because of the you see all the uh ecosystem and everything everything takes us with the with the having more understanding and more trust factor over there. So this is the beauty of enterprise ethereum alliance. So you should you know read this what is the membership FAQ how to become a member. So these these things we should go through I'm sharing this link as well and I am putting up in the chat plus in the document also. So whenever you get time so you go through this. Okay. Uh do we have and for this we do not have white paper. Uh if you are asking the Bitcoin one or the Ethereum Ethereum no white paper. So they are g they given everything into the documentation. I'll share that documentation. Okay. So now u this kind of you know collaboration it gives us more trust with the same. Now similarly you see if we see the applications multiple these domains the people you see JP Morgan they are from the finance background healthcare energy technology banking sector. So we see multiple players into the same domain. So uh Intel is also part of this Rajes. Yes, correct. But now they are also looking for a decentralized solution not for everything. See, once we come up with an understanding of all kind of a blockchains, we will ultimately conclude that blockchain is not solution for every problem. But it is solution for few problems and in that case blockchain is the perfect solution. So this is this is we can say a customized theory everywhere we cannot put blockchain. But there are some scenarios where blockchain is the ultimately a very good option or very good solution. So these uh you know companies and every they have at least one project they which is working into the blockchain domain. So you see Intel, Microsoft, JP Morgan, Asenture also we are seeing here. Uh similarly you see BNV, BNY Malen this is also a a good group. uh so these features we receive from the same second now now I come to the smart contract I come to the smart contract so as of now I just mentioned that smart contract is what it's just a program it's just a program but if I compare this program with any another language program it is entirely different not in terms of uh syntaxes or something obviously syntaxes will be different but in terms of running in terms terms of deployment. So we'll see uh today how it is different. Now when I say languages, so there are three languages that we use majorly into building up the smart contract. One is solidity, one is Julia, one is Viper. And if you see the market in the market Julia and the solidity is doing good and we are going through the solidity into our uh course calicul. So we'll be learning the same part here. Okay. Now before I explain you the theoretical part, let me take you to the how does the smart contract look like? Why I'm saying it is different. So what I'm doing all of you see it very carefully because I know that some of you are not from the uh programming background but we'll understand it in very very easy language. These are uh what percentage uh is built in solidity. uh Rajes it is not about the percentage I can say that if I need to give a probable idea so I can say that uh most of the IT companies they are looking for I can say that they're looking for the solidity engineer but even if you have the experience with the Julia you can apply for the blockchain engineer role so for especially for the Ethereum uh I have seen JDS in the India it uh solidity is also always preferred and also with the Canada and in some European countries especially with the research group they ask the Julia as well. Okay. Okay. Now see what you need to do what I do now I open this website into incognitive mode and I'll explain it why I'm doing it. So I'm doing control shift N and Remix. See this is the website remix.ethereum.org. Let me put up here as well. rimix.ethereum.org. So you see my screen first then I'll give you time to do as well. See first you will get up some you know cookies you need to accept. So I click on accept. Now you see first option you are getting here. In order to understand your need better, we would like to know how you would typically use Remix. So 1 2 3 4. So you choose here the correct option. So uh we will be going with the learning because we are at the learning stage. I click on that. So this is giving me a uh tour of the interface. You see here. So this is a welcome icon. I click on next. This is solidity compiler. Compiler means checking all the errors. deploy your contract. I'll tell you what is deployment. So this is my interface which I am getting for the program. Now you see there are certain terms that we will be using with this one case. So we know that what is folder? So in solidity or in remix I should say remix is workspace is a term that is given to the folder. Okay. Now in this case you see in this case you see when we say workspace folder now in that case what will happen? What is Remix? Remix is a IDE. ID is what? Integrated development platform. So I can build my entire program onto the same platform. Earlier it was available into two version. Desktop. Desktop means I need to install the software in my system and now it is more famous with the web- based version. So what is the beauty of the web- based? I do not need to do installation. I'll just put up uh limix.ethereum.org and it will be workable. Okay. Now in this case let me make it zoom like this. Can you see a contract folder here? Yesumin. Correct. Just like VS code. Can you see the contract folder here? Contract folder. All of you contract folder. Now whenever you are making a program, a new program, it should be inside this folder. It should be inside this folder. Okay? And what is the extension of solidity file? This is sol. So maybe whatever name you are giving you can give it something. let's say uh firsts or any another name you can give. So let me try to make a folder here or a file here. So what I can do I can right click and you see here new file and I name it first dot so and I click on enter. So when I click on enter now you see you see you have one page here you have one page here. So this is the place where you need to write the program. This is the place where you need to write the program. Okay. Now what we have seen but you see by default you are having only one folder. Folder is what? Workspace. Default workspace. So I can create my own folder as well. Let's say I click on this like here. Can you see this create blank or create using this and everything? So I'll go with the create blank. I go with the see how to make a new folder. Click on create blank and let me name it uh January 25. Click on okay. And you see here this time you're not getting anything no sample anything. So you can directly start creating there as well. So now what I can do there is nothing like a contract folder. So that time that is okay. You can just create it like this new file. So I will be making it let's say second. So that also you can do or another method click on workspace create using template. I click it again here create using template. So there also I can choose something like this. So later on we will try all these things here. Right now we are not doing anything with the sample. See can you see here basic and blank generic one these two basic and blank. So blank or basic we can choose. Let's say I can go with the basic also. So this I name it January 2025. I click on okay here. Now you see can you see the contract folder now? Can you see the contract folder now? Contract folder. See the uh panel there contract folder. So I will be making my file here. So what I'm trying to say whenever you are creating a new workspace what you will be choosing either you can go with the blank or you can go with the this generic template that is basic this open zeppelin and everything we will use later on okay not right now this is actually used for the uh fungeible token and the nonfgeible NFT creation so when you're using these samples that time you will be using this okay so Right now we will be working on to the either this basic one or this blank one. Okay. Now you see why I have asked you to run on the incognito mode. Now whatever I'm saving here, what do you think where it is stored? I created a file. Let me go back to this January 25. I created a file second. Where it is saving? What is the location of this file? What is the location of this file? So, it is being stored into my browser's memory. So, do we understand the cache memory of the browser? Cache memory of the browser, it is saving all the cookies and everything. So in case I delete history of my browser, see if I go with the control H, I do the history thing and I delete everything, my all the files will be deleted. So what is a deviceable? Now I'll show you my I'll I'll show you my Chrome browser. Now you see here this time I'm opening remix here. So this is not incognito mode. Now in this case uh Jagdish will that be saving in login credentials? Yes the Jagish correct correct. So whatever account you have logged in from now can you see multiple uh multiple workspaces here? Can you see multiple workspaces here? So everything is stored into my browser's history. Everything is stored into my browser history. Let's say I go with this July batch. I click on the contract and you can see multiple files here. You can see multiple files here. So these all programs are saved here. But this is part of what? This is part of my Chrome browser's history. And now you'll be asking what if I delete? So everything will be deleted. So it is better to take the backup of this. How I can take a backup? Now let's say I click on this July batch. Can you see this download option? Can you see this download option? The right click I have done. I have rightclicked onto the workspace and there is a download option. So with this I can download it offline as well or I can go through a GitHub also. Have you heard about GitHub? Have you heard about GitHub? So in the GitHub I can also publish. So I can use uh directly connectivity from you know from my remix to the GitHub. Okay, those who have not heard I'll just show you how does this look look like. So GitHub is a uh we can say a online platform that allows you to save your programs and everything and it will also allow you to create the version control as well. So multiple organizations uses it or they can uh you know they can also use a competitor of the same as well. So in this case you can make your account and you can also store your all the programs there. So what will happen in that case Remix will be directly connected to the GitHub and when it is connected by default from the same option I will be uploading onto the GitHub. Correct? Uh in case of GitHub do we need to make it public repository? No Ashwin, this is entirely up to you. You can make it private as well. You can make it private as well. All up to you. So I normally what I do I uh downloaded my system. Normally I downloaded my system. So uh nilashuri commit we need to do from the GitHub only. It will just will be uploading. Commit we need to do it from the GitHub. Can we also import the existing solidity program for GitHub? Yes, with that also we can do. So we do have you see open a file from a system, upload a folder. See there is a option this you can do from your local system. Similarly you can link it with sign into the GitHub. Can you see this? As of now I have not signed in. So once I have signed in that time I'll be getting all the choices. So I have not linked it as of now. I used to download it uh into my system only. Can we not store in our machine to begin with so that it not stored in browser history? Uh by default Ashwin it will be stored in browser history by default because this is a web- based platform and later on uh you can take the backups. Uh Saksham earlier there was software version but right now it is not working. Earlier there was a software version also. So let me show you Remix uh desktop or maybe you can try this older version as well. You can try this electron app. I'm sharing this l link. Uh Sakam if you want to try you can do that. uh but I prefer to work on this because we we we need to do you know metam mask connectivity and everything that time it is more workable for us okay so as of now whenever you are writing your programs I'll advise you that make sure that you're taking backup of of this or you're not just deleting your history like that and if you're doing it in incognito mode it will not be saving anything okay uh because ultimately completely the memory that is being used here that is the cache memory of your browser. Now uh do one thing all of you do one thing all of you do do one thing at least do be familiar with this open remix in your system open remix create create two workspace create two workspace name you can take anyone try deleting deleting one workspace Create solidity file in workspace. Try to download try to download workspace in your system. Okay, very small exercise. Just I wanted to sure that you are opening the your uh you're being familiar with the tool. Then I'll tell you how to write the program and everything. Does every uh Jagish remix on incognito mode means uh when we open our browser in incognito mode that is not saving any kind of a cache memory or that is not recording anything. So if you're not recording your program will not be saved. Does every blockchain has their own ID for the smart contract development? Yes. Yes. Sudesh uh like hyperledger fabric there we can work with the Eclipse also and also you know u we we can run the solidity program in visual studio as well. So that is also possible. So it's not like that fixed it is that uh some options are available which one you want to choose like for example Python is workable in uh Anaconda also Jupiter also or you can go with the Google collab. So we are using here web- based one that is remix. Okay. So let me give you this link again. Uh remix.ethereum.org. Make sure you open the correct link. Okay. remix.ethereum.org. Just do it this small exercise. So you need to open remix create two workspace any name you can give you need to delete one workspace uh deletion I have not told you so you need to explore this and then create a solidity file in the workspace make sure you are giving the extension as o to the solidity file and then try to download a workspace okay uh learning san choose the learning one so So you can go with the learning one. So this will be asking only one time. Next time it will be storing all the uh features for you. So it is displayed on the word file what you are supposed to do. Uh yes Jaganat Jaganat you share your screen I'll guide you no problem you share your screen I'll guide you that will be better so you have the rights to sh uh sharing as Yes, I can see your screen. >> Yeah, I'm in this page. >> Mhm. So, you already created a workspace, right? >> No, I have tried but I don't know what I'm doing. >> Okay, no problem. Let's click on this workspace. Uh on the uh below the file explorer left hand side top file explorer >> there is workspace there is three lines. >> Three lines there. Three lines. Workspace. Yes. Click on this. You click on create using bl uh template. Create using template. H. And uh then can you make it this remix AI down remix AI that is popping up uh on the right hand side right hand side there is a window appearing like this now. >> Yes. >> Just make it down. There is a icon there. Arrow kind of thing. Yeah. Now click on this basic create. Create. Yeah. So you can name it whatever you want to give and click on okay. >> Initialize workspace as a new git repository. >> No that is fine. That is fine. We are not initializing anything as of now. >> So now you see you have a contract folder there. this >> uh second one, second folder. Scroll down down this one. Right click, right click, new file. So this you can name your solidity file. Okay. Solidity files dot >> S O. Enter. >> Mhm. So this is the space where you can write the program. >> Okay. >> I'm not a programmer. >> Uh so I'll I'll give you the code and everything. Don't worry. So basically we we are understanding how this platform works. >> Okay. All right. Yeah. Thank you. >> H >> this much I had to do. This is my work, right? So I asked you to create two workspaces and then also explore how to delete one workspace. >> Okay. Can I do it now? >> Yes. Yes, you can do it. See there is uh there is a option. Okay, you create the other one then we'll delete. Okay. What do I have to? >> So any name you can take. >> So this is basically naming a file. every time just you need to make sure you're taking extension as dol nleshwari no we do not have any uh as such rules so you can take it and you can take the space as well so now I can download it also >> yes so this is you need to right click on this JD1 right click so this is for downloading. Okay, this is done. Downloading part is done. Now you try to delete one as well. >> Okay, so >> uh right click on JD Jan again. No, I'm uh I'm talking about entire folder will delete. Uh now click on that workspace thing where we got this thing now that lines. Yeah. Click on uh delete. Click on okay. So it is >> which one I have to delete is >> this is deleting your JD jam. >> Okay. Okay. >> Your current workspace. If you click on okay now you see you go to that drop-own list. Uh click on this Jagun Jan. So you see you are not able to see that another workspace. Click again. Only basic and this is available. >> Right. >> Okay. >> Okay. I have done it right. Thank you. >> Yes. Yes. >> Okay. Thank you. >> Uh okay. How to upload this folder to GitHub? Have you connected to the uh GitHub? >> Uh Jaganat, you can stop sharing your screen. >> Yeah. Thank you. >> Thank you. Have you linked to the GitHub? Log into the GitHub and then uh you will see that option. Okay. Uh Jagish I can I help you somewhere? Not finding any option to import the downloading. Uh Ashwin, have you connected it with the your GitHub or you want to do it to from your local space? from local. So local you can easily do let me see open a file from your file system. So if I click on this let me have something before. So let's say I download this 2.4 into my system into the download section and I have this open a file from your file system. I go to the downloads and you see uh so this is asking me to override or maybe I can rename it as well. Let me rename it. I make it sample or something sample. Okay. Now if we go back to the remix upload it go to the download sample and you see this is here. Oh no I think we'll be doing the one file Jagdish I believe you created with the blank. So in the blank you will be not be seeing anything like that. So that is okay. So when you are making the workspace there are two choices blank or basic. So if you're choosing the basic you are getting all these folders. If you're choosing the blank then it is a normal creation. So even that is okay. So you try with this basic one and you see uh Ashwin I think we can do it with the upload folder as well. Upload folder. Try this uploading folder as well. See whatever exercises we have with the Ethereum I'll advise all of you to please do that. You might be thinking it is very small small exercises but it is actually building your basics for the uh understanding the program and everything. In case anyone finding any issue with this uh please let me know. I can allow your screen share and we can mutually solve it. I'll be helping you out onto the same Yes s we I can do that. So in this case you see I ask you to make a new workspace. So how we can make it? So maybe I can start from the beginning. So this will be remix ethereum.org. Initially you'll be getting a option like which one you want to have learning or that platform maybe I can tell you that as well. So let's say first time if you're opening remix this will be looking like this you will accept it from this you will choose learning discovering web 3 development. I click on next next. This is just taking a tour for me. So this will be your default thing. Okay. Now what you can do, you do not need to do it in incognito mode. Just I did here. You will go with like this only. You click on this create a workspace using blank uh sorry a template. Click on the basic project. You name it whatever you want to give. Let's say I'm giving January 2025. Click on okay. When you have this kind of thing, you got a workspace there. You see you have a contract folder. Right click this and create a new file. Name it let's say first. This is your program name. Give a extension first. Solidity and click on enter. So this is the area where you will be writing the program. Then I ask you to make two workspaces. So let's say I am making one more. This is basic again. Let me name it February 2025. And I click on okay again. Maybe I can create one more file here. I'm naming it second. Okay. Then I asked you delete one of the workspace. So how I can delete? Let's say I want to delete February. I want to delete February. Now in this case what I'll do I'll right click and I not right click I'll go to this one these option you see workspace actions I click on this and click on delete this is delete workspace it is asking me are you sure you want to delete the current workspace I'll say okay this is being done now you see in this case I am left with only my one created one the other February is deleted from there. So I have given you task of uh you see creating two workspace we are done deleting one workspace we are done creating a solidity file yes we are done and the last one let's download it. So for downloading right click and click on download. So when I do this so it is asking where you need to save. So I click on uh let's say I choose my location downloads. Maybe it is directly downloading in your system. So the this is just setting of our system only. Same you can check up into your system as well. So let's say I choose into my system. I go to the folder location and you can see this is available here into zip format. So I extract here and I click on this. So you'll be able to see the entire folder here. See this is the entire folder. If I see contracts, so I'll be able to see the files as well. Okay. So this much I have done. Let me delete this down here. It's not having anything. I hope now it is clear. Sur. Okay. Uh okay. I missed the questions. Ma'am, let me just repeat. Surish. I'm done. It allows download workspace in GIF format but no option to upload the same workspace upload folder will upload zip file. Correct Ashwin you're right here how to use GitHub an you need to link it with your GitHub account link it and then you will be uh you know following up the repository and everything what is connect to the local file system option. So then you can make a hyperlink or make a link to your uh this one you are saying Nashin uh or where you are trying this which exact option let me see this and then I should tell you is done uh ma'am if accidentally no Shijan it is not possible so if you are uh be very sure onto this so I remember I have not deleted my history since uh I don't know how many years I always take the backup and still in mind I have this what is repository anumin which repository you're talking about GitHub repository or any another in GitHub so GitHub is basically it's a collection where you store everything so it's like a storage system it's like a storage system so we instead of folders. Uh we call it repository. Yeah, you can say that. But uh for the programming it allows you to have the same version. How many of you are done with this task now? How many of you are done with this task? Nilleshwari is done. Uh Saksham, Rajes, Svanan is also done. Sudh is also done. Vikrini, Jagish, Dhi. Perfect. Perfect. I believe all of us are done. Ashwin is also done. Uh right right correct. Now let me show you something how beautifully we can run with the remix. I come here to my own remix. Let me give you a very small program. Not I do not want to scare you. Uh this one. Okay. So, I take this from here. I create a new batch. So, new batch uh here and I make it basic. Name it actually January 25 2025. Click okay. go to the contract new file and I give it hello world hello worlds. Okay, I'll put a program here. Uh no, not ask CI and I'll cut it short as well. I'll just give a variable string message. I'll tell everything. Don't worry, you do not need to scare about this. We'll make the programming very simple. Hello world. Okay, I'll put a semicolon here and I declare it public as well. Okay, so as of now you see I do have some six line quotes exactly six lines let me make it five. So five lines code I have. So code part we'll understand later on but we want to see actually how this this you know execution happen everything. So now you see in this section all of you see this all of you see this you created a workspace you created a file you named it dos with the extension so whatever you want to name you have some four lines quotes here you pasteed that one case but what next what next now you see in this case see in this case can you see this solidity compiler here this green tick can you see this solidity compiler here green tick I click on this. So I just changed my interface there. Now in this case you see here in the solidity compiler what we want to do? What we want to do? There is something called as compile. Compile is checking that whether my program is having any error or not. Now what I do I show you something in this case. Let's say uh what I do here in this case there is a option autoco compile can you see this autoco compile autoco compile all of you there is a check on autoco compile I uncheck this I uncheck this you will decide what to do okay now I intentionally I'm making a error I'm writing something randomly there okay now as of now you are not seeing seeing any error. H I click on compile. Can you see the error now? Red line. Can you see the error now? The red line. Red line here. Okay. Now one more thing I do. I delete this. I save it and I again compile. Now can you see a green tick? Now you can see a green tick. So green tick is all good to go. My program is having no error. Red line is that this is having a error. Let me make 2 three error. 1 2 3 4 5 6 just I'm randomly writing something. I click on compile. So again you see this kind of s symbol will appear. Now what is the case of autoco compile? So let's say I'm writing a program and I want that it should check me parallelly. So what I should do? I should do autoco compile. I should do autoco compile. Now you see I'm making a error. Suddenly it got changed. Can you see this? When I made the error automatically it is updating here. So the green tick and everything is automatically com coming. So which is better having the autoco compile option or not? Which is better? Having autocompile option or not? Auto. Autocompile. So by default it is off. So you should make it on. By default it is off. you should make it on and how to make it on. So you go to compile section. So there is something called as uh I'll show it again. There's something called as autoco compile. So you need to make it check over there. This is one case. So now can I say that my program is errorree? Can I say that my program is error free? I can see the green tick with me. So this is running fine. This is working fine. But as of now I do not have any output as well. Next section. Next section. Now you see if we divide into the steps there what are we are following. So first case write the program write smart contract. Second compile it. Check for the errors. Next deploy it. What is deployment? Now we learn that. And then finally execute it. So we do have overall four steps. Uh anuman programming we'll talk about. We still need to understand all the lines. All the lines we need to understand. Okay. Uh now in this case you see move to the next tab. Next tab is deploy and run transaction. Can you see deploy and run transaction? Okay. Now in this case uh Manisha this is solidity. We are working on smart contract can be created with Julia Viper and solidity and we are using here solidity. Okay. Now in this case you see you have been shifted to somewhere maybe you have heard about for running the smart contract you need money. Have you heard about for running the smart contract you need money? Have you heard about this? So it's not free. It's not free. It's not free. So but the question arises when I am learning if I need to pay money why will I run this? When I'm uh when I'm learning why would I do this? And when you're making a software that time also you need to see that okay uh you know I need to do multiple changes. So we need a dummy interface. We need a dummy interface. Now I divide this into one called as test network, one called as main network. Now test network is with the help of dummy ethers. Main network is with the actual ethers. So in which case you are spending the money in the main network. So can I say that once my program is finalized once everything is sorted only then I should shift on the main network. Can I say that once my program is all sorted everything is done testing is done then I should go to the main network. So yes the answer is yes and don't worry I'll tell you all the steps of going to uh you know main network as well. We'll learn everything. So it is like a demo smart contract. Yesumin correct correct. Now in the same case you see can you see here some 100 ethers almost 15 accounts are there so as of now in my account you can see 1 1500 ether but I'm not rich here this is all dummy ethers these all are dummy ethers only so this is given to you to test your program as a test network okay uh I'll also tell you how this is you know how this money and everything is being decided So all all this will learn. So now I click on this deploy button. You can see orange color. Can you see this deploy button orange color? So I will be clicking on this and you can see some green tick here. You can see some green tick here. Similarly you see here there is something appearing here. Similarly, you see here something is appearing here and you need to expand this arrow. You need to expand this arrow and there is something which I have taken in a program message. This is like a button. I click on this button. I got a green tick back. Uh it has stopped somewhere. Let me come back again. So when I make it zoom, it is not going back. So let me run this. Hello world. So compilation is done. I go to the deployment section. Click on deploy. Expand this. And there is I am having message. So can you see hello world there? Can you see hello world there? Hello world. Something like a printing of my message. So this is the whole method how I executed my program. So what I did overall if we see our steps first we have written the program this is some four line quotes. Once we are done then we make sure to the compile. Once the compilation is done we got to the test network we click on the deployment and once the deployment is done then we expanded it like this and we were able to see our output. So this is the method how we will be running the program. So in other programming languages there is no step of deployment. There is nothing exist like a deployment over there. How do we do? We directly come up with this. So in our cases in uh solidity or in the case of remix we'll find four methods writing the smart contract compiling it deploying it and executing it. We have done deployment on which network? Test network or main network? I have done the deployment on which network? Test network or main network? Test network. So, we'll also learn how to shift to the main network as well. Okay. Uh I hope this is clear to all of us. The message button we are seeing under deployed is a function. No, Sudan, it is not a function. But still see it is just a variable. I have taken only a variable. See but still it comes like a button. Uh we do not need to use print or nowari we do not need a print statement. Can repeat the demo. Yes anuman I can do that. What was the difference between and deploy and ex execute? Rajes deployment is taking my smart contract onto this uh test network. So after the deployment I get to chance the execute. Execute is when when I clicked on the message. Execute is the time when you're actually seeing your output. Deployment is the interface which allowing you the execution part. So in case it is on the main network, at that time I need to do the deployment on the main network. Let's do it one more time. Those who got it, they can try it parallelly. Uh I'm sharing the program as well. See what you need to do. We start from the beginning. Um, so you have files like this. So you create a new file. Let's say I name it second. So I have the space here. I'll paste the code. Save it. Ctrl S. With the help of Ctrl S, I'll save it. I'll make sure this is compiled successfully. So you can click on autoco compile. Once you have this green tick, you move to the deployment section. In the deployment section, click on deploy button. Once the deployment is done, then you scroll down and you will be seeing this down here. I hope you can see this hello world thing. You can see this. So this you need to expand. Once you expand then you get a button like this. You click on this button. You should be able to see a message which we have passed through this. Okay. And I hope uh now it is understandable otherwise you can share your screen. I'll guide you parally. Perfect. Okay. So all of you try this. See as of now we have not done anything with the program. We just making sure that we should be familiar with the uh ID the remix only. So there are more things to learn about this and slowly slowly we'll be able to do that. Can't see the colors. Uh Jagish you need to click on autoco compile. Click on autoco compile. Rajes is done. Hmish is done. Vidya is done. Manisha is done. Great. Uh, Anuman will do this. This is just a warning. We can ignore it. This is just a warning. I'll tell you why it is required. So if even if I you know delete this from here now I'll be starting getting this warning. So you see this warning is coming like this. Ashwin is also done. Saksh is done. Shan is done. Uh Jagish, can you share your screen? I'll stop now. Seran is also done. Great. Uh yes. So yes actually it is not showing. Uh uh uh uh okay. Uh you create a file Jish and name it so in small letters. Go back to your file. Go back to your file. Which file you created? Contract. This rename it. Yeah. Yeah. Rename. Click on this pencil kind of thing. Make it so small. S O small. Enter. Now go back to your second dots solve the file. Now see color is appearing. Okay. Everything is good to go. Now who else is done? See as of now what we have done we just have seen how this remix is working and in this case you see uh we still need to know about the program we still need to understand the test network main network and uh you know later on we'll also see how we will be connecting it with the uh our platforms like meta mask or coinbase so all all of these things we'll learn so that's it for today you see we started with the ethereum and u This chapter will have more practical exercises where we will be learning about the programming and where we will be learn a brief of programming and we will more be learning about the connectivity with the different platforms like ginache metamas coinbase uh how to connect to the uh main network all those things we'll learn out all right so these next two sessions will be focused on to the ethereum blockchain uh anuman We can make a software for this software as in when I'm making a smart contract. Let's say I do have something called as a insurance smart contract health insurance land registry. So we can actually formulate the real life problems into the software. So when we are using it with the blockchain that time the transparency distributed ledger decentralization all of these things are coming together. So you might have heard about uh one of the IAT they had their voting their internal voting for some kind of members or something based onto the blockchain and recently um I remember I think I was going through uh Sep Shuklas's uh LinkedIn post. So they they just launched a attendance system based on the blockchain that is again with the Ethereum. So this is the way how this Ethereum or the smart contract can solve the real life problems. So you can think of a problem and then you can convert into the program. So rather than having a uh centralized server program I do have program that is based on the blockchain. Uh so now you see uh this is our course. Let me make it just bigger. Okay. So now you see the first course that we are meeting up. This is our fundamentals of blockchain. So in this case we are going to talk about multiple things. Basically theoretically major part we are covering with the theory. I'm not saying we do not have practicals. We do have multiple exercises rel to the practical as well. Then after completing your fundamentals part you will be taken with the course of Java. Java course will do. Then we will come to another course that is applications of blockchain or I can say blockchain applications and architecture. So in this case this entire course is mainly about the programming where we are going to learn how to implement Ethereum, how to uh implement hyperledger fabric, how to implement multi-chain and other technologies. Then in the last we do have capstone project. So I'll be telling you what is the criteria to get the certificate of each. But this is you see this way we'll go ahead into our uh diploma course RPG course. So you see first we are meeting up here for the fundamentals then we'll come to Java then blockchain applications and architecture and finally with the capstone project. Okay. So coming back to the first subject that is or the first module that is fundamentals of blockchain. Now you see what we are going to cover up here. So we do have some u approximately six chapters or six modules in this fundamentals of blockchain. What are they? So this course introduction is just a slight revision or a brief what do we have exactly? Then we'll come up come up to understand what is blockchain, why do we use it, what are the applications, why it is being demanded into market, why everyone is talking about the same technology. Okay. Then we'll come to the uh core concepts of blockchain which is applicable in all type of blockchains. So you might be you know this or not know that there is there are n number of types of blockchain. So whatever the common concepts we have we will be going through this into the pillars. Then after this you see after doing this chapter we will be coming to the next chapter that is bitcoin. So I hope everyone have have heard about bitcoin cryptocurrency. So it's not uh if you have taken this course you I'm very very sure you have heard about this cryptocurrency not others at least bitcoin so we'll cover the core concepts of bitcoin uh how the mining happens what is the algorithms that working behind the scenes or how how does the future looks like for bitcoin so all those discussion we'll do here then after completing bitcoin we will shift to ethereum blockchain so ethereum is one another blockchain where uh we are allowed to do programming. So programming is not allowed or not required in the bitcoin unless you are the bitcoin developer. But in the case of ethereum you can use it for general purpose. So let's say you want to build a healthcare record based on blockchain. So you can use ethereum blockchain. You want to build a system of voting with the help of blockchain you can use ethereum blockchain. And once you're done with the Ethereum blockchain, you will also come to the next chapter that is the enterprise blockchain. So enterprise blockchain is different from Bitcoin. It's different from Ethereum. Uh so its mainly purpose is to use for internal organization or having customers. So we'll understand everything. So by end of this course, you will be very very familiar with all those concepts of blockchain. you will be into the position of understanding. Okay, let's say in an interview they're asking you this is our problem. So according to you which blockchain should be used. So that understanding will only come once you know all the types once you know pros and cons of all kind of details. So this is our target. This is how we plan our fundamentals of blockchain. So this introduction to blockchain we are starting today. The second chapter we can say first first chapter of first module is just a course introduction. So that we are doing and then we will come to introduction to blockchain. Yes. This all we are covering up here. So we do have bitcoin blockchain chapter. So we we will talk about the cryptocoin liquidity mining everything. Okay. Now let me move ahead. So we do have uh you know we you all have got your LMS your ERP kind of dashboard there you can find out the ec content as well I'll take you there uh whatever the ppts I'm covering ebooks ec content everything is available there and for every course we do have some projects as well so I'll tell you what is the requirement to getting the final certificate also so that we that we also talk Okay. Now I'll start with the concept before I move ahead. What is blockchain in your understanding? What is blockchain in your understanding? So whatever comes to your mind, please put up in the chat box. Let's make the session interactive. Whatever comes to your mind in terms of what is blockchain, please write up in the chat box. Amushini this is ch uh this is decentralization chain of blocks transparent and decentralized data block connected with each other. It is a kind of application applied to many domains. Uh ri block and chain which create the chain of data. A decentralized form of data recording. Okay. H okay abishek we are covering all those concepts if you you want to do in mining or something that is your personal requirement we are mainly here to understand the concepts and the technology blocks connected in a chain it is mainly used to take cryptocurrency or token industry 4.0 O Rashid correct perfect perfect so I got uh multiple responses and that is perfectly fine you are very very close to what we are actually defining the blockchain okay so before starting this blockchain we actually need to understand one concept what is that client server architecture Okay. So now what is client server architecture? So I take a very simple example. So I'll open a page. Now in this case let's say this is I call up this is my laptop and on my laptop what I am trying to do I am logging amazon.in. So once I put the URL that page is displayed to me. Okay. Then I am you know uh ordering something I am updating something. So every time this is happening this particular my machine is acting as client. This my particular machine is acting as client and ultimately ultimately when I say that this request is going to whom? This request is going to server. This particular request we are transferring from client to server. Okay. So it means in the case uh yes s you will be you will be we can take these questions afterwards. Let's please concentrate on the concept that we are covering. I do not want you miss something. Okay. So what I was talking about I was saying here we are saying I do have client I do have a server. So every time we make request as a client let's say I want to surf a website Amazon Flipkart Mantra or any another website Netflix. So that time I am acting as a client. My request is gone to server of that Amazon of that company of that product. And where is this data stored? data about me, data about my product, data about any any another information. So this is stored into the case of the server. So every time request is coming from server and being targeted to client. Okay. Now uh now one more case. So when I say data where is my data where all the things are keeping up here? Now I'm saying that my entire data is recorded on what? On a server machine. So server is carrying all the data. So instead of calling it data, I call it the term centralized data. Now what is centralized data? What is centralized data? That we are keeping everything all together in a single machine. Maybe we can take backup of these servers. So let's say I have Amazon and Amazon is creating a repository where it is the data is centralized. Similarly, we do have multiple backups also. Backups means we are creating a storage point as well. We do have the backup points as well. So this term has been taken from that side. So now in the case of client server architecture we we say that everything yes everything at one place. So my entire data is centralized. Now the another term with the blockchain I'm saying this is known as decentralization. So decentralization. So what do we mean by this? Now you see in this case what kind of things we are imagining here. So let's say I do take it something like this. So I call it block one. I call it block two. I call it block three, block four, block five and so on. So we have heard terms like blockchain. So blocks are connected with each other like a train and this is actually storing the data. So when I say blockchain, what is the concept of decentralization? Why do we calling this? How it is different from the centralized one? So what is the difference between these two? Now in this case I say I do have 100 nodes. I do have 100 nodes who are actually part of blockchain. So in this case we discard the client server architecture. So no one is client, no one is server. The question arises then where is the data? Where is the data stored? So data is actually stored at all 100 nodes. The data is stored at actually at all 100 nodes. So I can say that this is just like a replication of data. So I'm saying the degree of replication has been increased or being induced in a such a way we are calling it a blockchain. So that is why now this concept is not a centralized one. This is a concept where we are talking about that my data is being distributed among multiple nodes. So I'm not only maintaining the part of the data, I am making multiple copies of the data and these multiple copies of the data are being formed into the every node of the blockchain. So this is the concept this is the very Sanji we'll talk about this also slowly slowly we are coming to all those concept right now we're just only talking about this is the concept of decentralization but your understanding is right who is managing that so every blockchain is different every blockchain is using different methodologies for that but we'll talk about slowly slowly on everything okay so now as of now if I talk about do you have clarity on centralized versus decentralized. Do you understand these two terms? What is centralized or what is decentralized? Do you all understand what is the centralized database and what is the decentralized database? Yes or no? Yes. Got it. Okay. Okay. Now you tell me Amazon is centralized or decentralized. Amazon is centralized or decentralized? Centralized. Centralized. And when I say blockchain, blockchain is decentralized. So again if I just come to the overview of the same thing. Now in this case what we are speaking up here. So when we say data is stored only on the server device. This is centralized. When we say that my data is distributed among multiple nodes, this is known as decentralized. So we just take a very simple example. Maybe I can write this. So centralized is the data is stored on server. The data is stored on server machine. And if I talk about decentralized data is or I can say data is replicated at multiple nodes. So I should write up here data is replicated at multiple nodes. So this is the concept that we are talking about. I hope those who have not got the clarity they they will be talk uh they will be understanding that what's the root it okay s node means machines node means machine could be laptop machine could be any another device so whatever electronic device we are using to store the data that is known as nodes so for example I am also part of the blockchain so this machine is node for me you're also working on blockchain and you have some data so this your machine is also known as node. Okay. Uh Abishek, do you got the clarity now? Sundep, I'll explain this different. So somehow it is same but it is having a minute difference as well. Okay. Perfect. Perfect. So now we know the first term that is centralized and decentralized. Now let's move further. So now you see what how this actually working uh in this case. So we will be talking about multiple things. one what is multiple things. So one case you see you have seen something like a decentralization then we'll talk about immutability we'll talk about capacity we'll talk about security we'll talk about uh group consenses we'll talk about the uh immutability again why that I'll I'll explain now uh when I say when I say that what kind of applications we do have now one one example we'll Okay. Uh have you heard about Walmart? Have you heard about Walmart? So not in India. So US it is having a very bigger market. Walmart is having very bigger market. So in in the case of you see in the year 2019. So they actually implemented blockchain for the transparency into the system. For the transparency means they want to have a you know understanding the food items which are coming from farms or which are coming from manufacturer they're actually the authenticated one or not. So they implemented the same thing with the help of what with the with the blockchain. So this is one of example where they have enhanced the transport and logistics into the case of blockchain. Similarly uh now I come to the case of banking and finance. I hope one of the application you can easily give it with me. What is the one application of blockchain? In the case of banking and finance. Banking and finance. What is the one application in the case of banking and finance? So cryptocurrency or we can say some uh digit digital tokens based onto the blockchain. So yes we we do have all these decentralization of exchanges. Okay. Similarly um how many of you know this uh one of Indian state already implemented blockchain for the land registry record. One of Indian state already implemented the blockchain for the land registry. Tangana. Yes. Karnataka. Yes. So you see so in in the in the case of this case you see already we do have implementation of blockchain into the government sector as well. So I show you one thing u maybe you can explore it later as well. So I'll give you reference for this because we are talking about the application. So we should be knowing that how we are taking a nationwise efforts. Yes, this was the link I was looking for. Now you see this is uh government website. All of you can see my screen. Ministry of electronics, MIT and information technology, center of excellence in blockchain technology. Okay. Now if you see the products we are talking about. So we have GSTs correct certificate chain document chain drug logistic chain judiciary chain property chain. So these all are name given as that certificate software or certificate application is implemented with blockchain known as certificate chain. Okay. Similarly, I'll show you uh states you see CBSC. So, CBSC we understand the document or the degrees or the u the certificates Andhra Pradesh, Chhattisgarh, Delhi, Karnataka, Maharashtra, Manipur, Ministry of Consumer Affairs, Ministry of Justice and Hudari. This is a UT. Now, similarly if you see what is in the proof of concept. So one of you was talking about GST. So you see Assam land records blood bank GST chain public distribution system and similarly if I see uh other things you see CBSC you can see urban property karnataka board pre university exam birth and death certificate. So we know that multiple levels corruption exist into the birth certificate and death certificate. You also have multiple examples for that for the same. I do also have uh Kannatka secondary education examination board and similarly we can see something like a supply chain management system for medicines in in in uh in the state Karnataka. So we do have multiple things. So this is I'm not taking uh I'll say I'm not taking my own record. This is the government record and you can see the number of documents which is being arranged or which is being managed by this blockchain that is also mentioned here. Okay. So you can uh go through this because we are talking about the applications. Let me give this link in the chat window. You can note it down or or otherwise I'm putting up this into the document as well. So this document I'll share. Okay. So we do have multiple applications with the blockchain. Correct. Correct. Now in this case I'll come to so we do have multiple applications in uh many another scenario. We do have one chapter as well where we are going to talk about these things in u in much more detail. But right now why I'm not explaining this because you do not know the type of blockchain how it is working. So before talking about the applications to relate the things it is better to understand the concept first then come back to the same scenario. For now we can understand yes we have a number of applications that can belong to uh transport department or logistics media and entertainment banking finance healthcare life services manufacturing whether it is industry 5.0 or we are talking about industry 6.0 O IT and telecom or the government one. Okay. Now uh do you have uh or maybe have you heard about IOTA or Hyperledger? I don't I'm not asking you know the concept or not. I'm just asking have you heard about these two? Uh yes. So I I do have mixed responses. I do have mixed responses. So this is you know we we can say what is trending in blockchain currency. So no cryptocurrency is associated with this. So this is actually for implementation for software purpose. So the good thing is that in our curriculum we are going to uh learn hyperledger fabric in very very detail so that we will be able to implement as well. So but if I talk about which is a promising sector into the case of blockchain. So these two technologies, one linked with the IoT devices, one linked with the we can say permission blockchain. So I'll tell you what is what is the permission blockchain. Okay. Uh what else? Okay. Somebody asked me what is the uh what do I mean by industry 4.0 or 6.0. So industry 4.0 was equipped with IoT devices. Uh in fact this is a very good term. We should talk about this. So one thing I'm saying industry 4.0. Now right now what we are working with this is industry 5.0. Then we say the future is industry 6.0. 4.0 was actually with the IoT devices. So we have sensors everywhere. Uh now you think of maybe you have watched web series and everything. I think one of the web series was family man or something. So in this case you see so we do have u kind of uh let's say a gas chamber and we do have sensors over there. So we do not need a 24 into 7 observation or supervision we have sensor devices to check that okay everything is under control or not. So initially when we say initially when we say we were not having any any kind of you know sensor devices. So that time human involvement is required and guess there is more chances of being error as well safety security but then we upgraded our industries our manufacturing plants our chemical plants nuclear plants and any other plant with the help of IoT devices. Currently we shifted from industry 4.2 to 5.2. So this includes what number one thing 5G, IoT, artificial intelligence and yes blockchain as but when I say future, what is future? Okay. What is the future of 5G 6G 6G? So already the research is being uh you know going into the same direction. So 6G included there and then we say that advanced AI advanced blockchain. So these all concepts are included with the help of IoT itself in the case of industry 6.0. So this is we are talking about a AI agents. Yes. Yes. Virat that is also part of that AI basically why I am putting up here AI is artificial intelligence. AI stands for artificial intelligence. So when when we say artificial intelligence what do we mean by that? So we have a technology that you know targets to train the machines in such a way that we we have something uh artificial intelligence. So when we say what is the broader term? The broader term is AI. Uh now can I say that Alexa is working based on AI models? Can I say that Alexa is working or Alexa or Siri is working on based on AI? So answer is yes. Answer is yes. One more uh question I can ask. So you normally go to Amazon, you're looking for u let's say a sneaker but you could not find a good match. You came back to your YouTube and you're finding the same kind of advertisement. So there also AI is working. So this is this is how uh machine learning or deep learning models are working. Okay, I hope this is clear. Now industry 4.0, 5.0, 6.0 We got the clarity. Perfect. Perfect. Now let's move further with coming to our back concept that is blockchain. So the trending terms we know IOTA and Hyperledger but as of now we just know it. We do not know uh know bigger details with that but we'll talk about this because this is our chapter six enterprise blockchain. So there we are covering this part. Uh no Sudesh this is only just example this is just only two example. So what is that broader term? Broader term is public blockchain, private blockchain. So that is the category. Then every blockchain comes into this this category. We are only talking about what is the latest one which is ruling into the market. So we have n number of types of blockchain. Okay. Okay. Now you see the structure. Now you see the structure what you can see in this all of you will be focusing here. We can see that one block is divided uh anuman IOTA and hyperar platform to build utilize blockchain technology to build application. Yes Ansuman correct? Okay now you see in this case you can see something I have a block okay and this block is divided into two sections. So what are these two sections here? What are these two sections here? In this case you can see this is header. This is body. This is header. This is body. Okay. So I have taken an example that blockchain is actually collection of multiple blocks. That is fine but that was all about you know multiple blocks. But if we individually talk about block, block is having two sectors or two sections. One is header, one is body. Okay. Now what do we mean by this? So when I say header, header is actually information about data. Header is information about data. Then I say body. Body is what? Body is a place for storing the data. Storing the data. I take a very simple example. Very simple example. So this is something like serial number or no arishi. Role number is 101. Student name is I ishu sharma. The course is fundamentals. Organization is simply done. So can I say that this is my data? Can I say that this is my data? All of you the yellow highlighted part. Can I say that this is my data? Yes, this is my data. Now this data I will be keeping into into the case of body section. one kiss this is the body section of what of block but when I say that I need some additional information about the data mark my line I need some additional information about the data so where I'm storing the data into the header set so now you see a very simple structure of the block okay we have a block into the blockchain we are dividing into two portion One is header, one is body. Body is carrying the data. Information about the data is stored in header. Correct? The information about the yes we we call it metadata. So in the technical language we say this information about data is actually the meta data. All right. Now what is meta data? But what kind of data I require? Okay. I have data but what kind of information I require into the data. So this is actually carrying up some information information like version of block uh hash of previous block merl root of the block timestamp everything it is carrying up into the header section. Now when I say what what are all those things? So let me pick one value here. Let me pick one value here. Now I say in this case I am taking up time stamp. Do you know what is time stamp? Do you know what is time stamp? Time stamp. Okay. So what is time stem? So when I say time stem it is carrying date time. All right. So if I talk about what is the time right now? So I say something this is 1844 uh today is 25th January 25 okay plus there should be some seconds also 20 seconds some microconds also 50 so this is my entire time so that is covering up and why do I require that so one of the thing one of the thing that we are including into the header is time stamp time stamp of what time stamp of creation of block. Time stamp of creation of block. How much time we have inject the data or change the data. Uh maybe you were trying to say something to identify the block. Correct? This is to identify the block here. So this is header is one of the thing. So now if I in this diagram I talk about so we have multiple things. So body body of the block is actually data. The case of header is what? This is meta data. In the case of meta data, I have one example. Other other things also we include. But one of the thing we have talked about this is time stamp. So time stamp we can say that time recorded at the creation of block at the creation of block so I take one more example now let's say coming back to the same story now in this say if I say here let me assume that in my blockchain I do have only three blocks in my blockchain I do have only three blocks obviously we have multiple others so I'm saying here this is also having header plus body this is also having header plus body this is also having header plus body in this header we will have let's say I only consider time 16 44 or we have time 1844 next block is created at 184 45. Next block is created as 1846. So this is recording the time period at the creation of block. Now block is what? This is block one. This is block two. Maybe I'm calling it block one. I'm calling this block two. I'm calling this block three. Right? I hope now you got the clarity. See, we still need to talk about what all other terms here are included. But we only talked about in header section we have a timestamp thing. Body section is all about data. Header is carrying everything related about the date. Correct? Oh, okay. Okay. Sorry. Sorry. I'm sorry. All right. Now you see in this case we only talked about header into the body sector. Now similarly you see similarly you see uh there is a term hash. All of you listen this very carefully. This is a very important and interesting concept. Now what I'm saying this is something like hash. Now what is hash? So I open a website that will give you a insight for this. Uh actually we have exercise also. Now you see can you see some changes here? I'm just putting full stop and deleting it. Putting full stop deleting it. Putting full stop. deleting it and like this I'm doing like this can you see the changes into the hash can you see the change uh changes into the hash all of you see it again this this this so something is happening with the hash now how it is happening and what is hash actually so we will also we have a chapter where we'll talk about this so we have something called as crypto graphic algorithms. So this cryptographic algorithms calculate the hash of your data. So this hash is what is this hash? This hash is an identity that your data has not been changed. Your data has not been changed. How this is happening we still need to discuss but as of now we are only understanding the term. So term is what? Hash hash is created with the help of cryptographic algorithm. Algorithm means you can understand something like a maths is working using some formulas using some theorems ultimately I do have a hash. Now this hash you see if you see full stop I'm deleting and I am putting like this. Can you find some kind of pattern in between? Can you find some kind of pattern in between? Is there any pattern exist? No, there is no pattern. It is something randomly appearing. I do not uh get anything how it is happening or how it is related to the something. Okay. So, this way we do not know. But I'm why I'm talking about hash. So in this case in this case changing even for some data yes even we you know check uh you see if I put I'm Dr. Ishu Sharma I put a one more full stop here. This is entirely cheat. So this this maths is not working on any kind of pattern. So it is impossible to you know get the hash values and everything. So this is in terms of security. Okay. So there is one term we talk about this is all blocks are connected to each other. All blocks are connected to each other. But how this is possible? Now in this case you see again I give you that same example. I have three blocks. I'm naming it. Let's say this is block one. This is block two. This is block three. All right. Now this block let's say this is my first block. It has some data. This is also having some data. This is also having some data. And also we talked about another sector is header. This is also header. This is also header. Data means it is part of body. Data means it is part of body. So the same scenario. Header section we have one more T. Now what is that? For every data listen this carefully. Let's say block one data calculate the hash. Block two data calculate the hash. Block three data calculate the hash. Okay. This is fine. This is we are doing for the security. Now when we are connecting our one block with another block, you see it like this block one to block two. How you are connecting with these? Block two is carrying block two is carry previous hash as block three is also carrying previous hash. So previous hash means what? Which block is before the block two? Which block is before the block two? Block one. Block one. So this block two is carrying hash of block one. Okay. Now with the same concept, block three will carry the hash of which which block? With the same concept, block three will carry the hash of which block? Can I say that block two? No. Only block block two. Yes. Similar to the link list. No, Anushi. And so it will be only carrying the block two. No commumulative adding only block two. It will be carrying only to block two. Now you see this exact see this this one. Now you see into this case. So same this thing we are talking about. No not first block. Now you see see this diagram block one carrying hash of previous block header. This is carrying hash of previous block header. So which is the previous block? B block one. Which is the previous block? B block two. So this is how the blockchain is formed. So every block is having the information of previous blocks as well. Let me show you one more example. This will give you more clarity onto this. Uh so sometimes shy if it is first block so that time this value is null. In case it is your first block that time this value is null. In case we have some value it will be carrying that correct correct instrument. So that is why you know security comes into the picture. Uh we go with one more thing here. Okay. Now you see this what we do? What we do? I'm writing here I am uh or I am just writing here this is block one this is block two now I just click on mine this is some automation and everything what is mining we we need to still talk about you match this now you match this this hash and this do you find it is similar match this one do you find it is similar Do you find it is similar? And why this is zero? Why this is 0 0 0? Why they have written zero? Because this is first block. So it is not connected with any another block. So that is why it is being shown as zero. Okay. Let me move further as well. Correct Vidya? Now let me go with the genesis block. Yes, the term actually we use this is the genesis block. I click on this mine also. I click on this mine also. Now you match block three and four previous hashes. Block three and four. Tell me it is same or different. Block three and four match the previous hashes. Same or different? Same. Same. Same. Correct. Now it makes sense. Now you see the blockchain how it is working. In this case you see so overall uh what we have talked so far that blockchain is collection of blocks. Every block is having two structure or two types that is one is header one is body. Body is collecting the data. Header is collecting the metadata. One of the header or one of the metadata is timestamp. Another we talked about the previous hash. Correct. I think it's it's all good to go with everyone. It's all good to go with everyone. What we talked about? All good to go. Okay. So, we all are at the same pitch. Great. Now, let me move further. Now, there is one more concept here. So, you know how this blockchain started. Merkel root we need to cover. Merkel root we need to cover because I want you should be knowing cryptographic algorithms first and then we should come with that. So we'll talk about that. Okay. Now the next thing I am talking about u how many of you have heard about cryptocurrencies? How many of you have heard about cryptocurrency? Cryptocurrency. Okay. anyone into the mining or anyone into uh I can say that so I believe Surish I'm completely into it. Okay. All right. So maybe some of you are investing or Yes. Okay. Great. Great. So now uh I I just want to recall a story. Now what is that story? Uh how many of you have heard about 2008 recession? That was something layman brothers 2008 recession that was a global recession at at the world level. So those who have not uh those who have not they should actually read this they should actually read this in case somebody because I I believe you know you have gone through that was a financial major financial crisis. So in this case what actually happened let me you if I I'll believe you. So what happened that time uh because of you know their their internal cryp uh their internal corruption and everything they provided loan to the multiple people those who cannot repay or those who cannot pay back and ultimately multiple investors they lost their money. the other people those who were divi dependent on that banks they actually lost their money and slowly slowly it actually turned up to a global recession. I remember a time even in India multiple companies the same time there was a company Satyam so that also you know bank corrupted so it was a major hit at that time so in this all situation what happened somebody took the benefit now who was that was actually the cryptocurrency that is Bitcoin do you remember which year Bitcoin was launched into the market bitcoin was launched into the market. So 2008 we have a research paper kind of thing where officially these things were you know talked about. 2009 they actually implemented as well and this was the same time period at that time what we were doing we were having something like we call that we were having that okay we have something called as cryptocurrency that could be a alternative to these banking sectors and where you can ensure your money where you can you know ensure your transparency everything you do not need to pay to uh to mediattors. You do not need to pay some resources to all those things. So you are the owner of your money. So likewise this is being this is being you know launched into the market. U white paper is actually like a research paper. Uh I can show you this as well. Bitcoin white paper. So whenever you know somebody from industry they are writing something about this. So this is known as white paper. Let me take you this. I'll share this link. You should go through this. Yes, this is the actually one. See this one. So you see this is a paper of 11 pages. And can you see this name Satoshi Nakamadu. Have you heard about this name? Have you heard about this name? So this is you know known as originator of bitcoin cryptocurrency and or the owner of the uh we can say bitcoin. So do you think do you think it is it is who who is this person? Who is this person? So do we know this? Do we know this? No. No. So this is actually you know anonymous identity. uh still there is there exists you know multiple stories about this who is Satashi Satushi Nakamoto or this is a group of people this is a group of team blah blah blah so we have multiple stories behind that but as of now we just know this name so you see this paper and this email ID is just given like this and this paper was launched or being published in year 2008 2009 they actually implemented the blockchain and can you see this diagram Here see this diagram we have gone through the same kind of concept. We have gone through same kind of concept. Yes, we do not know what is Merkel root. We do not know what is nons. We'll talk about this. But can you recognize this previous hash previous hash previous hash block header. So it is not including any body here because this is only given a description about that. So let me share this link as well. uh you should be going through this paper and in case you are not on some devices or something I'll be putting this in word document as well so you can go through this in later on. So now now why I talked about uh you know recession and everything. So you know every uh there is a story into the business that right time matters and for them also they actually picked the right time. When the entire world was going through this suffering they took that time and they hyped it into that sense that this could be one of the other alternative of our uh finances for managing the finances and today you see the bitcoin prices are much much higher into the same direction. Okay. So, but the term you say uh correct answer one the good one. Uh now you see when I say tokenization so this tokenization is you know one of the term uh very very you know frequent with us. So you might have debit card uh credit card or on GP also we do have reward system. So sometimes that rewards can be converted to money, sometimes like a shopping points, sometimes like some extra discounts or something. So this is all you know something which exist only digitally physically it is not available. So now coming to the same point cryptocurrency is not available in any hard kind of money. So what is the concept of cryptocurrency? What is actually the cryptocurrency? So cryptocurrency is we can say it is a digital currency. When I say digital currency, it means no hard copies available or we do not we do not have modes or I'll go to a ATM or something. So we have some digital currency that is cryptographically managed. Cryptographically managed with the help of blockchain technology. So this is a term about that. Okay. Similar to this, have we heard about NFT? Maybe you have. Have we heard about NFT? NFT gaming. Those who are into the games or something maybe they have heard about nonfgeible token non-f fungeible token. Now what is the difference between these things? What is the difference between these things? This is nonfgeible. I'll write the uh this as well. Nonfgeible token and another term is funible tokens. Funible tokens. So let me explain what is this. So basically when we say tokens or tokenization we do have two types of token in blockchain industry. One is NFT one is FT. NFT stands for nonfgeible token. FT stands for funible token. But what are the example when to use which one? So I take a example in this case uh I am I am um I'm a bigger artist. I know I'm not but I I can imagine. So I have made a painting and in that painting when I'm saying I am associating some funible tokens with that painting or I can say that I do have a copyright of something. Now when I say painting can I do it like that I tear it in half and give one to somebody and one I keep. Can I do that? Can I tear my painting in two parts and sell half of the part of that and do that? No, not possible. Similarly, uh now I imagine I am a music composer. So I have uh one song, this is being prepared. So can I sell some fraction of seconds of this uh this song to somebody? Can I sell some fraction of seconds or fraction of minutes to somebody? No. So either this I can sell it completely or I cannot sell. So situation is like that either it I can sell it or I cannot sell it. Okay. So this this categories come into the case of NFT. So I explain again. So NFT means something like uh what example we can take paintings, songs, patent. patent you know might be uh copyright so all these come into the case of nonf fungeible token okay but when I say cryptocurrency when I say cryptocurrency stamp yes when I say cryptocurrency which category it should come funible or nonfgeible when I say cryptocurrency which category it should come funible funible by funible so I can do that I have 10 uh 10 bitcoin. I can uh give one bitcoin to my friend. I can uh you know I can convert one bitcoin to Indian rupees. So that is allowed there. So this is the two category we are making up. So funible token is crypto currency. Okay. Funible is cryptocurrency and nonfgeible is something like where we are talking about that cannot be divided. Correct. But the lowest innovation is funible, right? Uh we can also change ownership of uh can I say just a second you can split one bitcoin as many parts and sell. Yes s right exchange is possible right but the lowest denomination is funimal uh right correct ashwin so every blockchain every cryptocurrency this concept is different. Can I sell the same pending to many? No shy this is not possible. So this is like a you know only one copy exist. We can also change ownership of painting right. Yes Sanjep that is the selling of the uh your NFD unique thing. It's like a copyright correct. Now I show you something maybe you have heard about this also uh Nike NFT. Yes. This is the thing I was looking for. I'll come back to this. Okay. Now you see, can you see the sneaker design here? Can you see the sneaker design here? So this, you know, Nike actually this this is a very uh good shoe brand. They actually launched their design with the help of uh OpenC market and they launched their NFT over there. Now in case somebody wants to buy this they can but obviously they will not buy but they created this NFT over there and why they created just to make a you know this is one of the u I can say marketing agenda and at the same time you know when they launched this NFT their share price market you know hype like anything. Let me again tell you the difference between these two. We do have two types of tokens into blockchain. One is fungeible token, one is nonfgeible token. Nonfgeible token is that can be that cannot be divided. Nonf fungeible tokens are that cannot be divided. So examples I have taken painting, songs, patent, copyright or u what else you can see design. So all these comes into the category of NFT. If I talk about funible tokens that can be divided. So the only difference is divided or not divided. Uh Ansum no we we cannot send the we cannot sell the screenshot or something. Everything is uniquely or cryptographically secured here. So this is all about security. Otherwise you can you know sue that company or you can sue that uh person over there. What is the use of the shoes or product listed Jagish? In this case, I just mentioned that this was a marketing strategy by the company Nike. And in this case, just after the launch of their NFT, they got a very good high price market into the stocks. All these are managed by the web three wallets. Correct? Now, let me show you one more thing. Maybe you have also seen this open C Now you see something. Can you see this picture? Elder God or this this this this and uh below to this can you see the price? Can you see the price? 0.5414 ethers. So everything is having price. Now let's say I I am I I want to launch my game and I want to have this character in my game. So I cannot take a screenshot. I cannot uh you know just save a copy or something. I need to buy this NFT. I need to pay this price. Then I can have it into my game over there. In case I do it anonymously or something, this company or they the owner of this NFT they can actually sue me or they can file a case against me. Correct Roi? Correct. So I hope now you got the clarity between uh between the case of block fungeible token and non-f fungeible tokens. Sanji this all is managed by the blockchain only. These all tokens are managed by blockchain. So this is NFT. If I'm talking about if I'm talking about cryptocurrency, everything is working behind the uh with the help of blockchain concepts. Okay. Okay. Now, so NFT again will come back you know uh what is the good thing? We will also somebody was asking from your side in our uh one of the exercise we will be actually learning how to implement how to create our own cryptocurrency. So we are going to learn that with the help of Ethereum blockchain there is not general management of the blockchain. So every blockchain is managed by other people other company owner. Let's say Ethereum, Ethereum company's honor. Hyperledger fabric they have the separate honor. Bitcoin they have the separate honor. So this is the uh things how the blockchain is working. The paint or the design is also gets deposited to the wallet after purchasing. Yes. Works on a consensus mechanium. Correct. All right. Now let me come back to this R PPT again. So tokens we understand. So I believe now all of us has the clarity what is the difference between funible token and non-f fungeible token. Do we all have the clarity on this funible versus nonf fungeible? Perfect. Perfect. Let's move ahead. Okay. So have you heard about ledger? So I'm not talking about blockchain now. Have you heard about ledger? Somebody have seen ledgers. So we used to uh you know uh at least in my childhood we used to visit some Kirana store and they they were managing the ledgers over there. We have one uncle or auntie she or he is you know uh writing writing everything on a register kind of thing where they are managing the stocks and everything. So this term has been taken from there after the ledger after that physical thing. Now you see uh what we have now we have moved to you know something like we called app uh spreadsheet or the software we have or we we can say that uh we we have some software like telly we have some software like in fact I remember there is one startup they are actually launching or they are selling uh kana people a app and that app can be used for managing all those records. Now similarly we have moved to one another term that is distributed ledger. Now what is distributed ledger? So this what is distributed here? So distributed means we're creating multiple copies of the data or now you see now you see this is the same term that I was talking about in this case you see if I do have some 50 nodes with me. So how many copies of data is uh calculated? How many copies of ledgers has been calculated? 50 50 same as the number of nodes. So I can say that 50 copies of ledger. So when we do have copies, I do have distributed ledger. Now you see one more thing. Okay, I have ledger or this is a distributed ledger. But when you see when there is a updation into the ledger, when there is a updation into the ledger, how many types you times you need to make that updation? When I say you need to update something into the ledger, how many times you need to create that changes? Again 50. Again 50. See 50 means you see you think of something. uh we are approximately 49 people into the class including me. So in this say you say I also have one data you also have your data and everyone is having that data. I'm having one record. So once it is being updated it has to be updated at all other locations as well. So this is what we can say that this we can say that 50 changes we need to do into 50 times. So this is the concept of distributed ledger. So in the case of blockchain we don't only say ledger we say distributed ledger for the reason being it is being divided at multiple nodes that is why we are calling this okay now there is again one term uh this term is actually related to client server architecture client server architecture now in this case you see client server architecture Yes, Jagish. It means we need to update at 50 places. We need to update at 50 places. Client server architecture is centralized or decentralized. Client server architecture is centralized or decentralized. Centralized or decentralized? Centralized. Perfect. Centralized. So, centralized. Client server architecture is that server is only one uh the concept of Amazon. Okay. Now when I come to decentralization this time we do not have client server architecture. What do we have? We have only peerto-peer network. What do we call here peer to peer network P2P P to P we always call it like that. So every blockchain is now it is not knowing as client server architecture. It is known as peer-to-peer network. Okay. In this diagram, how many nodes I have? In this diagram, how many nodes I have? Four. How many nodes we have? Four. Okay. How many copies of the data we maintain? How many copies of the data we maintain? Again four. Okay. How many distributed ledger I have? How many distributed ledger I have? Four. So all answer is four here. Okay. So I do not have somebody as server here. I do not have somebody as a client. We we are actually equal here. We all have the equal responsibility. So this is the case. You see in fact I was I had not seen this term here uh in the definition also if we see have equal responsibilities and access to the network resources. So this is the beauty of peerto peer network. So as of now you see how many terms we have seen in the case of blockchain. one decentralization second distributed ledger third peerto peer network one more term I related to uh I don't know how many of you are knowing this term or not in blockchain if I have written something listen this carefully in blockchain if I have written something I have something in my data that cannot be changed. So there is no option to the deletion. There is no option of deletion. Always always the versions of the data is created not the deletion of the data. So we cannot delete any data. So that is why it is said that when you're doing with the something with the blockchain, you need to be very very sure what you are putting up into the blockchain. By any chance let's say you uh you do not have you have made a mistake or something so you need to redo the things you need to create a newer version of the block. So this is the term is known as immutability. Immutability immutability means we cannot delete the data. So this is another term. This is the another term that we talk about. So you should be considering four terms as of now with the help of with respected to blockchain. One is decentralization. Uh let me just correct the spelling. One is decentralization, distributed ledger, peer-to-peer network and finally the immutability. Okay. So, Den in this case uh you know the basics of the concepts of the blockchain is entirely same but every blockchain is adding some extra benefits to their terms. So this is one of them. So they allow you to edit your basic details onto the onto the case of account section. So in case you have made mistake on creating your details so that you can correct there correct consumer. So if you have a wrong address you cannot any you cannot redo anything and you do not have any anyone like RBI or something to listen your complaints. I got it out. Since we do not have server where the codes are deployed, sundep the codes are deployed at every node. One by one we'll cover this thing. I know initially all those things will come to you but one by one we are covering everything. Okay. Okay. Now let's come to another term or uh important term. This is types of blockchain. Now what is types of blockchain? So we majorly divide blockchain into three category. One is public, one is private, one is permission. So what category I making? Public, private and permission. So to understand this I should show you something practical example. Okay. Okay. All right. See this is a website blockchain explorer. This is uh publicly given so we can explore it anytime. So what I'm going through all of you see my screen. So I'm going here latest block. What is the number of latest block? What is the number of latest block here? What number you can see here? 880767. 880767. Okay. Which uh cryptocurrency icon is this one? Which cryptocurrency icon is this one? Bitcoin. Bitcoin. So we we all recognize. Similarly, you see here in this case something is you know parallelly happening. latest transaction it's just speeding up like anything see 1925 and even if I speak I have newer transactions here okay so I'm not going with that I'm just going with latest block I clicked on this okay so when I clicked on this so this is I'm seeing multiple things here or something like blocks is also visible randomly I go with any transaction see this TX means transaction. TX stands for transaction. I click on this. Okay. So now you see can you see some transfer here? Can you see some transfer here? One account to another account. Can you see some transfer here from and to from and to? Okay. I just click on this also because these are all hyperlinks. What is the balance of this account? What is the balance of this account? Something you can see 91 91 USD. Okay. Now what I'm trying to show you with this I'm trying to show you with this that I do not know personally this person even I'm not aware this person belongs to a company or a individual. I do not know this person is actually uh Indian, Chinese or American or any anybody from which country this person belongs. But what do I know? What do I know here? I know the balance. Okay, not only balance, I can actually see the previous transactions as well. So I just got into the account. You see all those transactions are exactly visible. So you see how much amount is being transferred, how much is being added, how much was the fee, which account everything is available here. Similarly, this is all you know all interlink here. All interlink here. I again go to any another you know account. So there you can see some transaction. I again go to address and this person or this account is having zero balance plus I can see some multiple other transactions as okay so but why I'm showing you this all number one case we are talking about which cryptocurrency bitcoin so bitcoin is what a blockchain it comes into the category of public blockchain one case. So this is one example. Similarly, I go to one more website. This is ethercan.io. Don't worry, I'll give you all the links. Ether scan is for Ethereum blockchain. Latest block. What is the number of latest block? What is the number of latest block? What is the number of latest block? 2170 uh 1 964. Okay. Tough one. Yes. So this I again I click on I again go with this information. Now let me show you something very interesting. Um we go with this. I have something. Can you see here? 204 transaction and 71 contract. 204 transaction and 71 contract. Can you see this? So I'm opening that transaction thing first. Again I'm clicking on some random one. I I really don't know who is this person. I'm going to this from account. Okay. And if we see what is the balance here? Ethereum balance. What is the Ethereum balance? What is the balance here? Ethereum balance is 80 18.48 correct. So again I do not know this person but I can see all detail all transaction everything is easily visible. I come back to this contract thing also. Now what is contract? You you'll get to know about this also. If I see here this was something contract. I again click on this. I again click on this. I go with this. And can you see the coding here? See, can you see the coding here? I'll tell you how to, you know, get to know everything. Can you see the coding here? Source code, the complete code as well. So, that is also available. That is also available here. So now in this case you see what I am talking about. So this is Ethereum blockchain. Ethereum blockchain. This also comes into the category of public blockchain. Okay. The pros and cons we'll talk about later. Okay. Uh let me go through this. We use this website to check the transaction after transferring the coin. If the other party says he has not received the coin, can we take this transaction details and send us a prof? Uh s no we do have a wallets. So these wallets are managing everything for us. So like you have a wallet like metam mass binance. So there there's nothing like a screenshot or something. So these dashboards are capable enough to manage everything. Okay. This is some uh beside the address there is some name like yes Ashon I'll come to this in case if it cheats by transferring to someone we can track that also. Uh so our uh our wallets are managing everything. All right. So now you see now you see if I talk about public blockchain what is the property of the public blockchain? Can I say that details are Can I say that details are publicly available? Can I say that? Is it so? Am I correct? Details are publicly available. So the story is true with the Ethereum and the uh Bitcoin. Is it true? So yes, it is true. We have confirmed the same identity of users are anonymous. Can I say that? Is it true identities are anonymous? So do you actually know those person? Do you know what is that address? Do you know what this address belongs to? Which country or something? No, we do not know. So these are two properties of public blockchain. These are two properties of what public blockchain where we do talk about that these details are available there. So most of the cryptocurrency most of the cryptocurrency is available onto the public blockchain. This is the one case. Second case, second category we spoke about private blockchain. Private blockchain. Now you see see we still need to talk about why these details are public why this is happening. We have not understood the concept. We just know that public blockchain act like that. But we still need to discuss about this. Why we are not discussing now? Because we do not know most of the concept. We do not know what is Merkel root. We do not know how hash is calculated. We do not know public key, private key. So all those concept we need to understand first. Then we will come back to this question why this information is publicly available and one of you asked that uh some kind of names are written there. So these names are basically groups. Groups means rather than becoming a individual minder I can become a minor in a group also. So if I'm becoming a minor in a group that time I'm keeping a name for myself just like a dance group just like a group of thieves or group of a community. So that way they have taken a name but who is part of that team that is that nobody knows. Okay. So identities are still anonymous. So in case you are acting as a group you can keep your own name as well. So that name could be a pseudo name or uh it's a fancy name or animated name. So that that could be part of that. Now next thing the next category I'm making private blockchain. So what is private blockchain? This is entirely opposite to this one case details are publicly not available. Okay. Second thing. Second thing. Uh, so you can ignore my spellings things here because I but I'll still correct this available. Okay. So what I was mentioning here, what is the second point? We talked about the identities. So identities are every user is identified identified in this blockchain. Okay. So now I take a case. Uh this is a ERP or this is a HR portal of my organization. Listen this carefully. This is HR portal of my organization. Now what kind of environment you want? Private or public? This is a HR portal of your organization. What kind of environment you want? Private or public? Do you want to give some uh details publicly? Do you want to share your details into the case of all those organization? No, you will not. You will not. And it is okay to know the identities as well. It is okay to know the identities as well. So this is known as private blockchain. This is known as private blockchain. Another term we have gone through another term that was permission blockchain. Permission blockchain. Now what is permission blockchain? So it is also having you know uh when I say the same property, it is also having the same property. But what is the difference between these two? This is more strict. This is more strict. This has some uh we can say that lesser security or we can say that lesser permission is required. Lesser permission is required. I'll explain this with the example also. I'll explain this with the example also. Okay. What is that example? Uh what is that example? One case I'm taking RBI communicating with all banks. One thing banks are communicating with customer. Okay. Which requires more security or which requires more permission? Which requires more authentication? First case or second case? which requires more authentication. Correct. The first case. So this will be the case of what? Permissioned blockchain. This will be the uh Okay, I should write it here. This will be the case of permission blockchain. This is the case of this is the case of private blockchain. So this is the three categories we are making up. Now you see one public, second private, third permission. Now you tell me which one is used for cryptocurrency, which one is used for cryptocurrency? Which blockchain we do use for the cryptocurrency? Public. Public. Okay. Correct. public blockchain all the cryptocurrencies comes into the category of public blockchain but we still need to identify why this public okay but when I'm doing something for internal organization which one I can choose either private or permission depending on to the level of the application okay so that is why that is why these two terms private and to the case of permission is somehow called as enterprise blockchain also. So these two come into the category of what? Enterprise blockchain. So this these two are part of enterprise blockchain. So why I'm uh why I'm saying enterprise blockchain. Why I'm saying enterprise blockchain? Because normally we will be using it into industries only. Normally we will be using it into industries only. So that is why we're calling it enterprise blockchain. Correct. Correct. Used to develop enterprise platform. Perfectly. Perfectly right. So this I I hope this difference is clear to all of us. Public, private and permission. This difference is clear to all of us. Public, private and permission. Okay. So now I just have a quick overview what we have done. So we understood the terms like decentralization. We talked about client server architecture. We talked about block is having two parts header and the body. Body is for the data. Header is for certain things. One of the thing we covered time stamp. Then we covered hash and the previous hash. All the blockchain is connected with the previous block of the hash. So block through block three is having hash of block two. Block two is having hash of block one. This is the things we we talk about the connectivity. Then we have seen two websites. One is blockchain explorer. All the links I'll share and ether scan where we can see all the latest block latest transaction what is happening and we'll see more those things into these websites as well and we will also talk about how what kind of record they are maintaining. Then we made the three categories. One is public blockchain, private blockchain and permission blockchain. Public is for cryptocurrency, permission and private is for the enterprises. Okay. Uh second point, let me see this. Yes. So every user is identified in this blockchain. So in this case you see uh in public blockchain I do not know this hash belongs to. But when I say private or permission blockchain, so everyone knows in my organization this node I am handling. So you normally see that if I'm going to MNC or something, I have been alerted a laptop. So my logs are al always maintained. So they know that this particular machine is belonging to which particular person or IP address or any other thing. So they have my identity. Let's say uh I have been assigned with the ID. So they know my ID. So this is the indication of the same. It's like a internet internet. Yes. We can say that Virat yes there is a possibility. So when we talk about in terms of security uh public is more secure, private and permissioned is less secure. But we still need to talk about why because uh we we are still you know learning all those concepts. We were discussing about public private and permission blockchain. Let's see some examples. So Bitcoin is a cryptocurrency. Uh Ethereum is a cryptocurrency. Dash is a cryptocurrency. Litcoin is a cryptocurrency. So all these comes into category of public blockchain. So that we already talked about. Now you see the examples of private blockchain. So one example is multi-chain. Another example is block stack. Multi-chain we are going to implement. So we'll see how this blockchain works and everything with the help of commands and programming. So we're going to see that. So what as of now you just know the example. Example is multi-chain or block stack. Okay. Now you see which which one you can see familiar one from these three example which is more familiar we talked about earlier as well which which seems familiar there hyperledger hyperledger so other examples are in the case uh where you have ripple also R3 CUDA also so might be you have heard about all these three maybe you have heard about two of them or none of them. So case varies from the situation but these all all example of uh you know this and you know u I was giving you example of Walmart. So Walmart actually using hyperledger fabric I can show you this. So they have given you know one case study as well. See this is also a Harvard business review. You can see how Walmart Canada uses blockchain to solve supply chain challenges. Similarly, how Walmart brought up unprecedented transparency to the food supply via hyperledger fabric. So this is also one of the case you know they have come up with I'll show you one line they use. Yeah, this is the tagline they you know have in the case study for mangoes in the US. The time needed to trace their provenence went from 7 days to 2.2 seconds. Can you imagine 7 days to 2.2 seconds? What do you what kind of uh you know impact you see on the business with this? What kind of impact you see on the business? Then from 7day tracking to 2.2 seconds. So now you can see that this transparency is actually having you know a lot lot more onto onto the industries uh and that is why organization like Walmart they included such a case and we have any number of other examples as well but this is one of them efficiencies correct okay so this you can easily find out you just Google it this term Walmart hypology fabric you'll get multiple things so which whichever article you uh you know more related one you you can go through that. Okay. Now I come to the case now see this is can I say that this is client server architecture. Can I say that this diagram belongs to client server architecture? Yes. So this is a centralized system. So we're not talking about the decentralized here. If we see the example for decentralization, this is something like we can see this one. Okay. So, how many nodes you can see into this peer-to-peer network. How many nodes you can see into this peer-to-peer network? Five. Five. And where I do have decentralization to the system, distributed ledger. Everything is replicated. And we do not have no one as client, no one as server. Everyone has equal responsibility. Okay. Uh okay. Now I take a example. Uh we should discuss this. Let's say by any probability. Let's say let's imagine a case this is being failed. This is a machine. Machine can fail any time. The server has been failed. Do you think now these clients are still able to get back the data? This machine is a fail because of some hardware failure, disaster or any another reason. Do you think these clients will get the data? These clients will get the data. No, they cannot. If this machine is failed, so I can say that my entire data is of having loss over there. Now, same kind of situation if we see into peer-to-peer network. So in this case of peer-to-peer network I say that my node three is a fail. My node four is a fail. My node two is also failed. Do I still have the data or it is lost? Do I still have the data or it is lost? We have we have so we have the data node one and node five. It is still having the copy of the data. In fact the last term which I'll assume here. So this will be at least one node I should have to have the you know copy of the data then I can get back my data. So now with the same logic which architecture centralized or decentralized is promising for the higher availability which architecture is more promising for the higher availability obviously the decentralized one with this with this logic that is why we always use a term that is known as high availability. Okay, second thing increase trust and transparency. Obviously with the same reason we have more trust. Uh now you I ask you a question. In fact I'll give you one u you know one real life incident example as well. So I think few days back I was speaking to one of my friend and u he is working in a government organization. Obviously I not named that. Now they do have the biometric system to keep up the attendance. Biometric means ultimately that attendance has to be recorded on a software. But now this person is having a good uh relations with the the employee who is taking care of that software. Now he does not go to the office at the right time and he connects with that person and that person is marking his attendance on that part. Now you see we made a biometric system for having the uh you know function punctuality into into the offices or anywhere but we do still have the lack over there because we have loopholes. Similarly, now I ask you a question. Uh, imagine you have a bank account in HDFC. Do they have right to delete your all entries? Not legally. I'm talking about maybe illegally. Do they have permission or do they have power to delete your all entries? Can they do legally? I'm not talking about illegally. They can. Illegally. This is a system. This is a system. Obviously they will not do because every all of us are you know linked with the trust and everything but as a administrator they have all the rights. Similarly uh you uploaded certain photographs onto the Google drive can anyone who is actually having the direct link of that database can they see your data? Can they see your data? if they are actually you know linked with that same database can they see your data yes they can yes they can similarly uh let's say I I applied for admission and I uploaded my all degrees so now this degree is you know accessible by all those concerned people over there so now in this in this all scenario when we compare the blockchain the blockchain concept is entirely So if you do not have right you you cannot see the data and if you are seeing the data the owner is also you know owner is also aware about that part. So what I'm saying let's say my degree is listen this carefully my degree my document is on a blockchain portal. So you need to ask permission to me to view my degree. In case you are doing that that record also I do have. So I'm I'm very very sure about that. Okay. What is happening with my data? Who is having the access when that person is seeing and everything. Now same thing can I ensure into the centralized system? Same trust can I build into the centralized system? The answer is no. There is there is no possibility like that. So that is why when we say here transparency and trust is concerned with the blockchain. Why privacy and security? Because we do have uh cryptographic algorithm. But we still need to understand what is cryptographic algorithm. As of now uh you know as of now this is just a term for us. So these are some benefits of decentralized system but the major one is higher availability. Okay. Okay. Uh can you relate something with the transparency? Any any feature of blockchain which ensures the transparency? Immutability deletion not possible. Now with this case you know see it cannot be altered. It cannot be deleted modified. So this is also ensuring this is also ensuring that we do have transparency into the system. So nobody can delete my data because versions of the data is available. Let's say uh in this case by any chance somebody is trying to do this manipulation. I do have versions of data history of data can be checked everything this uh every time this is available. So we do have all the records with us. Okay. Now I come with the same concept pseudo anomous C correct. Okay. What is blockchain forking? Uh now when I say forking in this case what is a forking? Have you heard about this term before? Have you heard about this term before? Fking. Fking. Yes, GitHub it is related to. So now what is forking? Uh in in this case sometimes what happens in cryptocurrency? Uh do you think cryptocurrency is regularized by any law? Do you think cryptocurrency is regularized by any law any RBI or uh you know any anything like any centralized organization? No. No. Nothing is like that. So now u is there a possibility? I have one blockchain that is you know working since last one year and one day I am the owner of the blockchain and one day I decide to discontinue. So can I do that? Can I do that? This is my organization. I do not want it further. This is my organization. I do not want it further. Let me give some lame reasons and I am uh I'm shutting it down. I'm shutting it down. So it is it is possible. Okay, this is one case. Similarly, now what is for forking actually? Now let's say before one year I was working on algorithm one. Algorithm one means in fact I take a real life example. There is a concept of Ethereum 1.0. Ethereum 2.0. So Ethereum 1.0 O was working on a algorithm that is algorithm that is proof of work. What is proof of work? We will talk about this. In fact, this is a very good term. Now 2.0 shifted to proof of stake. POS we call it. So two terms we take here proof of work and proof of stake. Earlier Ethereum was working on proof of work. Now Ethereum 2.0 is working on proof of stake. So it means I had some forking. Fking means what? We shifted from one algorithm to another algorithm. Now how we are capping up or how we are ensuring that everyone move from the older concept to the newer concept, it depends on blockchain. It is the responsibility of the owner of the blockchain. But the term when we say that uh term we say here proof of work typic I mentioned proof of work this this we still need to talk about this is this is actually part of mining right now I'm not covering up I just have taken example you can consider it as algorithm one or algorithm two also so forking when I'm talking about so forking is something we are changing certain things we want to change certain brain thinks and that time we can use a plan fork. So forking in a blockchain happens when a blockchain splits into separate chains. I divided something. So each following its onoff rule often due to the protocol upgrade community dispute and network glitches. Now in this case in this case change white paper uh Deepak I'm sorry I could not get it what you're trying to say please elaborate okay now in this case you see one more example I'll take this was let's say 1,000 blocks from 1,1 block it is based on algorithm two that is proof of state till 1 th00and block it was based on proof of work. Okay. So now can I say that two separate chains? Can I say that two separate chain? So now you tell me uh block number 900 will which will belong to which chain? First or second? Block number 900 will belong to which which chain? First chain 1.0 0 that is working with the proof of work something like U 1200 it will be linked to which chain 1 1200 Ethereum 2.2 to an proof of state. So this is the concept that we cover up with the with the case of I can say with the uh forking. So we do have very you know uh all those examples that exist with that. But I'll come back to this topic once we understand proof of work and proof of stake as well. As of now I can just let you know that the mining when when we talk about the mining or a miners that concept is based on proof of work or proof of stake. In fact I should write a full form as well because some of you could be very new to this proof of work and this is proof of state. Okay. So when this these two terms are actually associated with the mining concept proof of work and proof of state. Okay. Now let me talk about one more thing with you that we should cover today. Okay. See three things we should be very very much clear on to that part. One is cryptography. Second is consensious. Third is distributed ledger. Now you see this uh the good thing is that in this consensus we'll talk about mining also. We'll talk about proof of work also. We'll talk about proof of stake. So by this chapter you'll be get to know about all those things and you know you know uh once you have understanding of this consensus that time you will also understand why it is necessary to have public blockchain for cryptocurrency. This also we'll cover. Now I'll come to cryptography and this is a very interesting topic. This is a very interesting topic. Let me start with this. Okay. Now in this case you see and also you see one more thing uh cryptography is not only for blockchain many another fields are also using it. So these are very generic terms that we going to learn about. How many users you can see into the picture? How many users you can see into the picture? Two. Two. One is Joel. Second is Maria. So I call this Joy. I call this Joy as sender. I call this person Maria as receiver. Okay. So I have two people Joel and Maria. So in this case you see one is sender, one is receiver. So what is the message here? You see hello Maya is a message that has to be sent from the side of join to Maya. Okay. Now uh when I say these things so when I say cryptography cryptography is what we are giving some kind of decoding what is the decoding here what is the decoding here uh might be you all have done some you know aptitudes test or something let's say I represent hello with something like number as xq W E or in fact I should keep same for W. Okay. Now can I say that H is replaced as X. E is replaced as Q. W is replaced as sorry not W. L is replaced as W. And with the same story, let me take it on the next page. O is replaced as uh here. Okay. O is replaced as now you tell me O is replaced as R. O is replaced as R. So we do have R here. So you see here how we are matching up. So we have done some kind of coding. We have done some kind of coding. So we use two terms here. One is encryption, second is decryption. One is encryption, second is decryption. What is encryption? Coding the data. What is decryption? Decoding the data. Okay. Now let me ask you one thing. Let me ask you one thing. So I add one thing here let's say I is represented let's say I is represented as 75 okay so now let me give you this coding let me give you this coding I'm highlighting this now tell me how high will be written hi with this quoting how high will be written hy H I what should I use for this? If I am following up this coding, what should be followed up for high? X75. X75. So what you have done? You have done encryption. I am decoding the same. So this is decryption. So two terms we talked about one is coding the data. Decryption is decoding the data. Okay. Now do you think this encryption decryption is a good method for data security? Do you think this method of encryption decryption is a good method for security? Yes, of course it is. Yes, of course it is. Now why? One more example I'll give. Uh you might remember earlier WhatsApp messages was were not encrypted. Earlier WhatsApp messages were not encrypted and now you see you we have you know received emails uh you know we have received advertisements and everything like that. Now encryption is possible on WhatsApp. So now what what is what do you mean by encryption? Instead of sending my data like hi, I can send it like x75. Instead of sending my data like hi, I send it like x75. Now see the example which I'm taking it is very simple but otherwise for encryption we use very solid methods. We use multiple other methods to have these encryption over there. Now in this case basically what we are trying to understand in the case of cryptography we do have some choices. What is that choices? Can you see this encryption here all of you? Can you see some encryption here and the decryption? Can you see the encryption and the decryption? So yes we are doing up here into the same case. Okay. One more term we see here signing. Uh now let me ask a question. How your check got verified in banks? How your check got verified? Checks that we have here signature. How from signature they verify it? How from the signature they verify it? So when I let's say I created my bank or something that time they have taken uh you know my signature and when they see it on the check they're actually matching it. They're actually matching it. Am I correct? They they do the same thing. So this is now signing and the verification. So we have four terms into the picture. We have four terms into the picture. encryption, decryption, signing and verification. So these all four things comes into the area of cryptograph. But what we want to secure now I do not have check I have data. So on data I can do the encryption, I can do the decryption, I can do the signing, I can do the verification. But how but how do we do this? Now in this case we see we take two keys here. In the keys we take two keys. One is public key another is private key. So let me assume here one is public key. Public key and private key. Okay. Now public key now just you remember I'll tell you how how do we use just remember two things public key it can be shared private key it cannot be shared. So now you have two things public key it can be shared private key it cannot be shared. Okay but how do we use this? So we divide cryptography in two categories. We divide cryptography in two categories. One is symmetric, second is asymmetric. One is symmetric, second is asymmetric. Right now in the market we are using the second category. Right now in the market we are using a symmetric cryptography. So obviously asymmetric is more secure than symmetric. Now you see let's understand the case of symmetric here. Let's understand the case of symmetric here. So what I have done here in this case they're using only what public key. They're using only public key or we can say that this is something like a private key which is which is common for encryption also and decryption also. What do I mean by that? Okay. So let's say let's say I have a data. See I have a data. So this data is known as plain text. We call it plain text encryption is being applied on data using using I call it shared key. Okay. Then decryption is applied on data using shared key shared key. So now you see that this is something like that uh I have a lock that lock is having a key. Now this key is being shared by sender and receiver group. Okay. So what I'm transmitting into this case we what I'm transing into this case and also you see one thing this is known as cifher text now what is cifher text what is cifher text okay so let me call it like this my data was hi Maria we applied shared key on this. We applied shared key on this. Now this has been converted into let's say uh ZXCV. So this I'm calling now cifer text. Two terms I talked about. One is plain text. What is plain text here in this case? What is plain text? Can I say that hi Maria is plain text? What is plain text? Can I say that? Hi Maria. It is my plain text. Okay. What is cifher text? What is cifer text? What is cifer text? Z xcv zcv which I have received after the encryption process. Which I have received after the encryption process. Okay. Now, so now in technical language, in technical language, can I call that now you see we just create a definition. Can I say that converting plain text to cifher text is known as encryption. Can I say that encryption? Can I say that? Converting plain text to cifer text. Is it? Yes. According to this theory, what will be decryption? According to this theory, what will be decryption? Now you tell me vice versa. Vice versa, what is the vice versa case? So I can say that converting cifher text to converting cifer text to plain text. This is known as decryption. Okay. So we we got the correct definition with us. Now now let's say I do take a table again. In this table I consider this as sender. Sender was join. This is as receiver. Receiver was Maria. In same example what was the data? Data was hi Maria. This I'm also calling plain text. Now I have a key. Key is shared key. Shared key is applied on plain text to get the cifer text. Okay. Now with the same story you tell me which what will be communicated plain text or cifer text? What should be communicated? Plain text or cifer text? What should I send into the communication? Plain text or cifer text? Cifer text. Correct. Very good. Cifer text. So this is traveling. Now in this case you see they are not sending the plain data because of the security attacker can have it. They can actually know what is the data. Now this is the same thing. Uh let's say a terrorist is planning a attack. So they know that phone calls and everything is tapped up. So instead of saying directly bomb they're using some keywords they're using some other language they're using some uh sign language or something to communicate. So then they are using what encryption they're using a cifher text and on the communication what is there not the direct data the cifher text is there. So now what will be communicated cifher text and shared cifer text and shared key. So now receiver is receiving what? Shared key and cifer text. What we need to do decryption. How we can do the decryption with the help of shared key. So ultimately what we will receive plain text. Ultimately what we will receive plain text. But in this theory, in this theory, now you see what is bad, what is a limitation. Don't you think this is also at a risk? If we are sharing the shared key also, don't you think it is also a risk? What is your thoughts on this? I'm doing a symmetric approach. I'm doing a symmetric approach. Now in this case you see uh we are sending the key also. So we were saving the data but key is also available. So the attacker could be very smart. They just use the zipper text they converted and uh they can be hacked there. There could be any kind of possibility. So this was the story of what symmetry key where we were using the shared key. So now for the same reason let me show you example. Um you see here this is example for symmetric key. Uh all of you do with this me generate a symmetric key. So I'm just clicking on this. I'm saying give me a key. What is key? All of you remember this. I'll not remember that. What is key right now? 124. Okay. So you will tell me now. I'll go this. Go back. Go back. Go back. Like this. Let me write a plain text. Plain text means a message. So I write that hello Maria thing only. Hello Maria. What was my key? What was the key given to me? What was the key given to me? 124. I write here 124. I click on encrypt message. I click on encrypt message. So can you see that something cifer text is provided to me. So this is what encryption this has been done here. Now let's decrypt the same message. I copy this cifer text from here. I paste it here. What was my symmetric key? What was my symmetry key? 124. I click on decrypt. Am I getting back my message? Am I getting back my message? Yes, I'm getting. So let me try something else. I make it uh 130 randomly I'm doing this. Now what you can see can I get back my data? Can I get back my data? No. No. In fact, let's make it 125. 124 + 1 just to see this. So I got some message. But this is is that message? Is it my plain text? No, this is not my plain text. So everything is good about symmetric key but the only case is that when we are sending the symmetric key with the communication that that is not making a sense. How do we come up with this key? In our earlier example, hello and hi. What would be the key? Ashwin, that time we were taking a very simple example like we just replaced a with something or we replaced H with something some coding kind of thing. But in actually we do have u math mathematics working behind to generate all those keys. So based on that key my data is being changed like this value. uh sudesh yes you can consider it with the case of hashing as well. So uh we we do have multiple keys like that. So in actually mathematics is working behind that. So that is converting my data into some other strings. Okay Ashwin I hope it helped up. Okay. Uh do you want to try this the same website at your system? a quick try. Let me give you this link so you can generate your symmetric key and just let me know once you are done. All of you just 2 minute exercise uh play with this website and come back. Same example you try and once done please let me know as well. Correct answer. So everything happens with the help of cryptographic algorithm and this is why we are going through this because in the blockchain also everything is uh being secured by the cryptographic but as of now we do not know the concept. So that is why we starting from the scratch. See in this classes we'll have very small small exercises as well bigger exercises as well but everything is for your learning uh might be you feel it like that okay it is very simple don't do this but this this all exercises are actually making your concept stronger so I'll advise be attentive in the class complete all the tasks which is assigned to you yes this is like uh encryption algorithms as or DS we do use Rashia that's correct done okay so I believe all of us are done with this now let me thanks for the confirmation all of you I really appreciate okay now let's come back to Ashwin that cannot do the calculation so this calculation also has a limit and this is just a dummy website to show us how these things work. Okay. Now let come to the symmetric cryptography. So asymmetric cryptography is a advancement over symmetric. Symmetric was using shared two. This is using two combination of now listen this very carefully because this is the actually we're using with the blockchain. Now see here let me close this. This is not required. Now okay. So in this case you see I will be using two keys. One is public, one is private. Okay. Which one can be shared? Which cannot be shared? Now you tell me which key can be shared and which cannot be shared. Public can be shared. Private cannot be shared. Public can be shared. Private cannot be shared. Correct? Okay, we remember this thing. So now we are good to go. a symmetric cryptography. Now in this case what we say every user gets or every user or machine anyone basically every individual gets gets keys into combination. Combination means public plus private. Okay. So when you go to market do you buy uh lock and key separately? When you go to market do you buy lock and key separately? No. It it always comes into the pair. It always comes into the pair. Same kind of pairing we are expecting into a symmetric cryptography as well. So we say that it always comes with a pair public and private. Okay. So now in this case you see come back to this picture user we have two Maria and Joy. This is Joyel and this is Maria. Encryption will be happening at the side of sender. Decryption will be happening at the side of receiver. Okay. Now see this picture. So according to this picture I say Joel also having combination of public key and private key. Maria is also having a combination of public key and private key. Done. Okay. Now which can which key can be shared? Public or private? Which key can be shared? Public. Public. Okay. Public can be shared. See, not both. The private will not be shared. Okay. Now, in this case, you see u can I open generally I'm saying uh let's say it's a very very good company. Can I open a lock with another key? Can I open a lock with another key? So, ideally no. Ideally no. Uh logically I'm not talking about ideally no. Okay. So it's like a good lock. We consider that list this lock will be openable by its own key. Okay. Now in this case you see what we are doing. We are using public key of Maria. We are using see this carefully. What we are using? We are using public key of Maria for the encryption. What we are using for decryption? Private key of Maria for the decryption. Now let me explain this because you can get confused with this but I'll make it easy for you. Now in this case you see same story. The story is saying that Joyel and Maria, Joel is sender, Maria is receiver. They started with a communication. So it has public key. I'm writing here PJ public key of joy and this is private key of joy. again public key of Maria and private key of Maria. Okay. So they got it into a pair. They need to do communication. Communication plain text cannot be used. What we needed? What we needed? We need cifher text. What we needed cifer text. Now Joel asked Maria first before sending anything. Joel asked Maria send me what? Public key. Public key of Maria. Why only public key? Because only public key can be shared. Okay. So, Maria send joy the public key of Maria. Now how data plus PM PM stands for public key of Maria has been used to form the cifher text. Okay. Now do I need to send any key now? Do I need to send any key now? Any key should be traveling? No. Why? No. Because this data will be opened by which key? This data will be opened or decrypted by which key? By the private key of Maria. So I do not need to send anything. What is required now? What is required now? Only send what? Cifer text. You see text that is being used with private key of Maria to get back the data. Correct. So now you see this is the beauty here why we are asking the public key of Maria because ultimately we do not want that private key should be shared. So that is why only public key has been traveled and p private key has been kept at as safer side without doing any kind of communication. So now you think of one more situation I'll give. Uh you have a visiting friend in your house and that person is having some meeting or something and now suddenly you need to leave your house and you need to go somewhere. So you're handing over a lo lock lock to him. You're handing over a lock to him. Lock is having a number lock. Have you seen number lock? Have you seen number lock? Yes. So now I know that I have the number lock with B. So what I asked my friend, you close the door, you lock it and I'll I'll I'll see. Now you see I have not shared my private key. I only know the key there. So in that case lock is also done. And I got my uh no keys as well. I do not need to share with anything. And uh one of you are asking how does Maria receive private key. So Maria Sanji she's already having it once she has logged into the system. So when you create your account on uh we have portals we have software. So these portals generate public key and private key for us. These portals generate public key and private key for us. So it is initially prepared only. The only concept is there that this private key will not be shared. Public key can be shared. Correct. Correct. Public key will be sent by the sender rule. Can only by sent by the receiver. Correct moan. You're correct here. So first place will be asking what? Asking receiver. Purpose of a symmetric shorty in this case. See, symmetric cryptography was not safe, was not secure because we were sharing the key. By with the help of a symmetric, we are able to have the security of the key and still we are able to get it. And you see the same key, same key if I use here PJ, this cannot be used for decryption. Decryption will only be done by the private key. Lock can be done by public key. But opening the lock can be done only by the private key. Right? Now I hope you got this concept. Now you see this diagram as well. See this diagram. If you have any confusion please let me know. Here in the case of cryptography we have gone through symmetric cryptography. Asymmetric cryptography we understood the difference between public key, private key, encryption, decryption, digital signature or I can say that verifying, signing and the verification process. So this we have covered into the case of cryptography. Then we move to the consensus. So the case of consensus we basically spoke about uh oh yes this is this was the Merkel root as well. So we it was known as the root hash that also we understood and then the consensus we focused on some problems and then we came up with the solution. The one problem that we discussed that was two generals problem then we came across Byzantine general problem uh the fall tolerance part we discussed and finally we started with the proof of work. So I believe in you missed your class or something so you were able to watch the recordings because see this course is not something uh we can say that you miss your one class or you miss your one concept and next concept you can easily get no that is not possible. So everything is based on to the previous concepts. So proof of work we have a fair idea where we discuss that first the users like us they are making transaction. Let's say I'm sending some bitcoins to my friend and this is a transaction. So transaction initially enters into unconfirmed transaction pool. Once it is entered into the unconfirmed transaction pool miners pick those transaction from that pool and they propose a block. So they will not only have only one transaction they can have the multiple transactions into that block and uh that depends on the size of we can say size of a block. So averely into the bitcoin the average size of a block is 1 MB. Accordingly the number of transactions are being decided over there and then the proposed block is looking for that getting the approval. So before that miner has to solve a value we can call it nons. Once the nons is solved in minimum number of or minimum time the minor gets the chance to form the block and then it is being sent to or broadcasted to the or we can say one to many kind of relationship happens with which the sending of the proposed block is to the multiple nodes. after it gets the confirmation of 51% then it starts with the adding up the block into the final blockchain. So that is why you see in this diagram we have miners, we have block, we have block puzzle. Can I call this as nons? Can I call this block puzzle as nons? Can I say that? Okay. Now proof of work, broadcasting the new block to the network, verification by other miners and process start over. So this is the final thing and also we talked about that the in the case of proof of work we are speaking about bitcoin and in the bitcoin we have a price money of 3.125 bitcoin plus transaction fee. So this 3.125 bitcoin who is paying 3.125 bitcoin who is paying and who is paying transaction fee 3.125 bitcoin who is paying and transaction fee who is paying bitcoin community correct correct transaction fee sender perfectly right perfectly right uh I just close this so I can say that these are minted, new bitcoins are minted, the term is minted and this has to pay by the users. Okay. So as of now this process we we perfectly understand. So I believe uh proof of work is clear to all of us. Proof of work is all of to clear to all of us. See you might be thinking that I am focusing more onto the proof of work. The reason behind every other consensus algorithm is actually based on two proof of work. If you are not having clarity of this, you cannot move further. So that is why I'm asking multiple times. Okay. All right. Now you see after doing this let's move to the things here. So we have talked about that in proof of work we have references to the previous block set of transaction is there. What is the full form of nons? Non stands for Non stands for number that is only used once. Number that is or you can say random number also number that is only used once. Correct? Okay. Uh now let's talk about the next concept. Now what is that next concept? This is mining pool. Okay. So what is mining pool now? So now we know about the proof of work process. So in this case you see I actually need a very high infrastructure to solve the nons or I can say to get the correct nons I need to have a very good infrastructure. So when I say good infra I'm talking about my physical resources uh an I come to this I'll come to this I'll come to this so we line by line we are covering everything okay so we are starting the bitcoin chapter today only and the first topic that we are starting that is about the supply of the bitcoins okay now in this case you see if I'm saying that I want to become a winner. What is the probability? I need to invest into good infrastructure. If I have a good infrastructure, obviously I am at the winning stage. Okay. Now, second case, let's say I I cannot afford this much infrastructure, but I really want to do Bitcoin mining. So, is there any possibility? So, the answer is yes. Now, what is that answer