It’s easy to think that the internet is something like a one-way mirror; you can look in, but that unless you’re posting comments, sending emails etc. that nobody can look back at you. Well, that’s not really the case.
When you want to look at a web page, the server that it’s on needs to know what information to send out, and where to send it. So, for example, for your visit to this site, there is some information that you have had to send, which can easily be recorded. < ?php
echo "
Your user agent (that is, the is type of operating system and web browser that you’re using to see the page) can be identified as “. $_SERVER['HTTP_USER_AGENT'] . ““;
echo “
The page you came here from was “. $_SERVER['HTTP_REFERER'] . “
“;
echo “
Your IP address is “. $_SERVER['REMOTE_ADDR'] . “
“;
?>
Many websites rely on the ability to “remember” certain information. For example, when you log into a website, it’s obviously important that when you go to a different page on the site, it somehow knows that you’re still logged in under your own account. If you add something to a shopping basket then leave the site, it’s helpful if it’s still there next time you visit the site. If you choose to personalise a website in a certain way- for example, to change the number of results per page that a Google search shows you- then you want it to stay that way when you come back again. Or if you see an advert that leads you to buy a product, then the advertiser wants to know, because that’s the only way they can judge whether they are getting value for money from their advertising. (Especially if they are the kind brand who cares about their image and doesn’t want to litter thousands of websites with flashy and obtrusive advertising…)
To make this “memory” work, most sites will use cookies.
Cookies are simply small text files that are saved on your computer. You can see what’s stored in them- you will have a “cookies” folder somewhere on your computer which you can look in to see what cookies are being stored on your machine, and you can look at what information is stored in them by opening them up in a simple text editor like Notepad. Usually, these will mostly be things like unique numbers which correspond to an entry in the web servers’ database, identifying your computer with your online identity.
As is usually the case with technical matters, the level of understanding about cookies amongst most consumers is probably best described as “confused.” (more…)
November 29th, 2007 | The Internet, Web Content | 1 comment