Away From Prying Eyes: Analyzing Usage and Understanding of Private Browsing

Previous research has suggested that people use the private browsing mode of their web browsers to conduct privacy-sensitive activities online, but have misconceptions about how it works and are likely to overestimate the protections it provides. To better understand how private browsing is used and whether users are at risk, we analyzed browsing data collected from over 450 participants of the Security Behavior Observatory (SBO), a panel of users consenting to researchers observing their daily computing behavior "in the wild" through software monitoring. We explored discrepancies between observed and self-reported private behaviors through a follow-up survey, distributed to both Mechanical Turk and SBO participants. The survey also allowed us to investigate why private browsing is used for certain activities. Our findings reveal that people use private browsing for practical and security reasons, beyond the expected privacy reasons. Additionally, the primary use cases for private browsing were consistent across the reported and empirical data, though there were discrepancies in how frequently private browsing is used for online activities. We conclude that private browsing does mitigate our participants' concerns about their browsing activities being revealed to other users of their computer, but participants overestimate the protection from online tracking and targeted advertising.