As we browse the Web, our browsers picks up cookies. Many sites will give our browser advertiser’s cookies. More importantly, the advertiser’s servers can look to see whether we have their cookies and where we obtained them. This is how they record our browsing habits. The more places they advertise, the better they are able to track us.
Collusion is an addon for Firefox detects the cookies added to my browser in order to identify the parties tracking me across sites are. For example, I just installed it and visited Google which dropped cookies for doubleclick, rubicon, bluekai, and others. I then went to the New York Times web site which added Nielson, Doubleplex, and other such as doubleclick.
This is going to occupy me for days… Maybe even weeks.