How Cookies And HTTP Referrer Tell A Site A Lot About You

More and more, people are starting to get freaked out about how much it seems a random web site knows about you. Sure, you expect to go to a web site such as Facebook and for it to be able to suggest items to you based on your preferences. You gave them a lot of information about yourself when you signed up and it also sees the post that you make. But when you go to a random web site and it offers information about you that it shouldn’t know, it can be a little disconcerting. Well we are here to tell you that it is not magic and it is based on commonly used technology.

How Cookies And HTTP Referrer Tell A Site A Lot About You

The technology that it is based on is a one two punch. One of the technologies is known as Cookies in your browser. The other technology is known as the HTTP Referrer tag. Let’s describe a little about what each does and then
we can show you how it is used in your everyday web browsing.


The HTTP-Referrer system is an interesting piece of technology. It allows a web site to see which web site sent you to it. For example, when you type a search term in Google, it sends you a list of web pages that matches that keyword. You then pick the site which seems to most interest you. You then go there. The web site will then see in its HTTP-Referrer tag that Google is the site that sent you.

The HTTP-Referrer tag is part of an overall bigger Header system. There are all sorts of commands that you can use in the header system. It is what allows the internet to work as well as it does.


Cookies are a technology that allows a web page owner to store data on their user’s computer for a certain amount of time. That data is usually used to keep information about that user’s activity on the web site. It is how a web site knows whether you are logged in or not after you leave the site. It will also store other information about you such as what you last looked at and what your name is. It helps to personalize the site for you.

As you can see, with these two technologies, a site can learn a lot about you. It can see the site you came from so from there make a reasonable assumption about what you may like. After that it can then use the Cookie technology to see and predict even more.

About Lee Munson

Lee's non-technical background allows him to write about internet security in a clear way that is understandable to both IT professionals and people just like you who need simple answers to your security questions.

Speak Your Mind