s3p2

1) The document discusses three ways that social networking sites can compromise user privacy: lack of control over activity streams, unwelcome linkage between online personas, and deanonymization through merging social graphs from different sites. 2) It provides examples where users were surprised because they lacked control over what events were shared in their activity stream or who could see it. It also gives examples where unintended links revealed private information. 3) The document recommends designing social networks that give users explicit awareness and control over their activity streams and linked personas to better align system functionality with user expectations.