How much does THE INTERNET KNOW ABOUT YOU?
Quite a bit, actually.
Visiting this site will display a list of all the most popular websites that you’ve visited.
The difference is that the site is paying attention to which of those 1000 links would appear in a different color because you’ve already visited those sites. You know, that funky purple link instead of the nice blue link you normally see for a site you’ve never visited before?
So the site is not displaying links for sites you’ve never visited, and doing a fancy graphic display for sites that you have been to. Simple, isn’t it?
Now that you know how it works, go send the link to your friends and scare ’em a little bit.