Social network sites, privacy and the blurring boundary between public and private spaces

With social network sites (SNS) becoming a pervasive phenomenon, already existing conflicts with privacy are further intensified. As shown in this paper, online and (once) offline contexts increasingly conflate, thereby posing new challenges to the protection of the private sphere. SNS quickly evolve their features and challenge privacy preferences, often without user consent; 'social graphs' make social relations highly transparent; social plugins interconnect user traces from within and outside the SNS. As the large amounts of personal information available in SNS are processed with context-rich information, the individual's informational self-determination is heavily strained. These data attract potential and real observers for behavioural advertising and also for profiling by security authorities. We argue that the emerging usage of SNS (social plugins, increasing role of biometrics and mobile computing) multiplies privacy challenges as all types of privacy become affected. This raises additional demand for public policy to foster privacy-by-design combined with awareness-raising mechanisms to improve informational self-determination.