The White House may have misled people who visited its website about how it tracked their online behavior.
In a forthcoming paper, a group of researchers write that thousands of top websites, including WhiteHouse.gov, have been using a new, persistent type of online tracking.
But according to the the paper, which was first reported on by ProPublica, the White House site and other sites have been using a firm called AddThis, which used a form of tracking different from cookies.
Like cookies, the AddThis "canvas fingerprinting" technique builds profiles of users based on which websites they have visited. But that tracking technique is harder to block or opt out of than cookies are.