As we browse the web we are tracked by ad-networks, social networks and other third parties that build (supposedly) anonymized and incomplete records of users’ browsing histories. This talk will first discuss the threats resulting from web-tracking by describing how these records can be de-anonymized. Then, we will overview existing solutions to prevent tracking with a focus on the work done in the W3C Tracking Protection group. We will also quickly overview privacy-preserving mechanisms that could be used to support behavioral targeting. In the last part of the talk we will discuss another type of threat: photo tagging on social networks. We will quickly overview the proposed mechanism to protect privacy of pictured persons. Finally we will present Photo-Tagging Preference Enforcement (Photo-TaPE) which helps users to control how their pictures are published on the web.