As part of the experiment, 52 thousand user profiles were analyzed, which can be accessed by third parties and websites. As a result, it was found that the preferences in visiting sites are constant, typical for users, and unique in 99% of cases. It is noteworthy that the user profile remains unique, even in cases where the sample is limited to 100 popular web resources.

The Mozilla experiment lasted two weeks. The information obtained for the first week was compared with the data for the second time period. As a result, it was possible to re-identify 50% of users who visited 50 or more sites. If users visited 150 or more sites, successful re-identification was recorded in 80% of cases. The test used 10,000 data simulation web assets that are available from major content providers such as Google, Facebook, and Verizon.

The study showed that the owners of large resources can identify users with fairly high accuracy. We are talking, for example, about the companies Google and Facebook, whose widgets are often placed on third-party sites. In theory, they can re-identify users with an accuracy of 80%.