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I've always read that cookies can, and do, store sensitive information such as OTHER websites that you've visited outside the one to which the cookie belongs.

I've started to read up about it and can see that it's persistent cookies which typically do this - and well I've started to look through cookie files on my computer - but I can't see any telling info in them! Just a few jumbled lines and not the scary urls of other sites that I'm looking for.

How do I view them? Or is the raw data of visited urls only ever stored on the server end of the site that's tracking me?

I'm on Win7 and can look at cookies from FF 12, Chrome 18, IE9 and Safari 5.1.

Thanks for illuminating this once and for all.

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The cookie themselves does not contain the data, what the cookie has is a GUID (A unique id) which corresponds to record in a database somewhere. That is where all of the tracking information is stored. The cookie is just used to tie you to that entry in the database.

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A tracking cookie doesn't store any information in your computer, it is used to identify you.

A website stores a unique ID on your computer in form of a cookie. Now, each time you visit websites that have access to this cookie, you can be identified. The logs are stored on the server-side.

This is usually used to keep track of browsing habits (visitors of site A are likely to also enjoy site B), but if one of the linked websites has your personal information, it could easily give away your identity on unrelated websites (user U just read an article about topic T).

In order for a tracking cookie to be effective, multiple websites have to have access to it. Such a cookie is called a third-party cookie (the first party being the website you're visiting). All mayor browsers have an option to allow cookies in general, but disallow third-party cookies.

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Thanks guys, so let me get this straight: it's only websites that do LOTS of third-party content serving on other sites (ad sites, google/facebook/digg/disqus (etc) commenting platforms/social bookmarking/iframe integrations), that are really a problem? And the way they work, is this?: I visit site x (facebook), and it stores a cookie with a unique id on my pc. I then visit news site y, which has a facebook integration box where I can see my face inside it, and when I do this facebook accesses the SAME cookie (if you simplify it), thus records that url that I visited, on its own servers? – user78017 Apr 1 '12 at 10:32

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