Follow the Cookie Trail - Computerphile

Key Takeaways

everyone's Heard lots about cookies um they're an interest it's a it's a funny term it's an interesting word um people see them and increasingly what you'll see is you'll see that little window pop up on websites in Europe which says we use cookies to enhance the user experience and please click that you accept this so why is that window there what's happened well cookies are great at enhancing the user experience and worth talking a little bit about what that means and but they're also obviously there is a little bit of a warning so are they good or are they bad let's start by what are they well the way in which underlying worldwide web works is that essentially it's a distributed system okay which means that there are places that hold information and there are things that ask for that information so your computer say which should look a little bit like this with you would would say please give me something it would respond and say here you go so if you imagine a page in on here that says hello the information for that page would come over here and would appear in your screen and we've done this lots of times some machine say in your house is asking a machine in Australia for this information the very first protocols the very first means by which this is has done took a very simple means of doing this what they decided was that they would be what's called stateless so this machine would simply say it's a new page here's a page here's a page what that meant for for you as a user would be if you went away came back had a cup of tea and then went to the exactly the same place and ask for the same information there would be no knowledge whatsoever about you having done it before which became a little bit silly so how then do you do the little shopping carts there's often a little a little shopping cart in the corner and as you go through and you buy things it puts things in the carart well how would you know that if you don't remember who's asked for the information and what they've asked about so that's what cookies are about the world now changes so let's now put a cookie in so imagine you you're on this page you say give me the page and you get the page with all the details but you also within that will have little tiny files called cookies cookies allow this machine to remember information about the last page it gave you which means as you purchase things they can be added to this and so that when you go away and come back that information is remembered so preference can be set you can decide things so layouts of things can be can be done which usn't to happen before so the whole thing from end to end gets called a session so it's no different than putting your shoes in to be repaired and the man gives you a ticket and then you go back and you use the ticket and you get the right pair of shoes back so this all sounds good this enhances everything but they have started to become really quite controversial as well the real issue about this actually you probably best have a think about a web page here many web pages that you go to give you information for free and have you ever wondered how people can do that why can you get something for nothing well what happens often and increasingly you'll see this is you'll see a web page has been a bit like this and then there'll be the content that you're looking at there okay so in my case this would be stuff about fball okay so I'd be looking up my favorite team's football scores but I'll notice all these scrolling ads around here the adverts are generating revenue for that page in order to do that and that's where cookies get controversial the example I've given you is what's called first party cookies when one party is given an information to another what actually happens here is rather interesting cuz you see in one page but actually what's happening happening is a range of things this could be the part where you're asking for this page and you're getting the content but all these adverts could be coming from completely different parts of the world and often are okay so these can all are all companies which are selling up the ad that means that the web page although it might be wwwmy favorite site.com all these other sites are also putting information into that page so this can enhance the experience by remembering Who You Are by putting a little file down all of these when they put the information down are also putting a cookie down so now all of these advertising agencies also remember that you've been on this page so these guys can start to talk to each other and then form an advertising Network which can start to remember your preferences and where you've been on the worldwide web this is basically known as tracking or cookie tracking these thirdparty cookies allow the advertisers to figure out have you seen this advert before and even to sequence a number of adverts so they can decide that some adverts and some things that people purchase they purchase after seeing a sequence of adverts and they can do that sequencing because they've remembered where those things are we probably do need to know just how much people know about where you browse how you browse and what your browsing purchases are because many many millions or billions of sessions can be analyzed so are you the person who browses in a particular way are you somebody who purchases things in a different way so all of these cookies allow little trails that can be knitted together and analyzed to understand your behavior and that's why the EU introduced as part of their privacy measures this thing called the cookie law and the cookie law said well you've got to inform people that you captured information about them and then allow them to opt out so those little screens that appear do that there are still problems here one of the problems here is the EU have legislated for this so this has been browsers in the EU if you try and go to the same sites you probably won't see those things okay but the interesting thing about those is it's either cookies off or it's cookies on many people talk about perhaps what you want to allow is one party cookies but not third party cookies as always with computers these things can all be done and even in the current systems you can do most of these they're very difficult to present to users and very difficult for users to find so so you will if you really want to dig down deep to be able to do this but it's not quite as obvious there's also quite a lot of scare stories about cookies cookies are not programs okay when cookies go into your machine they don't run as code so that means they can't really give you a virus which is be one of the dangers that people would have they can't um in and of themselves take over elements of your screen or even your webcam the worry everyone has though is the start of allowing all of that to happen without anybody noticing and there's been quite a lot of controversy about this and and people don't realize that so if I ask you the question do I'll ask you now so how many of these cookies and many third parties do you think they'd be on a site on one side on one on one page one site um I'm going to think you've simplified that but you've got three or four I say maybe um six or seven okay so so so the interesting thing is every one of those gives you a tiny amount of money