In January 2016, Princeton University researchers Steven Englehardt and Arvind Narayanan sent outrequests to the top 1 million sites on the internet to see how web users are being tracked. They assembled the largest dataset ever used to study web tracking.
Web tracking happens to every internet user whether they know it or not. As someone searches or browses through websites, they are interacting with “first parties” (the websites that the user is visiting directly) and “third parties,” which are hidden trackers like ad networks that can access users’ browsing history employing tracking technology like cookies.
The Princeton study found that news sites have the most trackers, with an average of 40 third parties recorded across 100 of the top sites.