Security and Privacy in Web 2.0 [Guest editor's introduction]

Over the past decade, the Web has morphed into an interaction and user-content-rich environment. For many online users, the Web has become a routine and integral part of their daily lives. For some, it has even become an extension of their real-world existence. With this heightened interdependence on this instance of the Web -- Web 2.0 -- we must pay special attention to the security (and privacy) of both the foundation and the set of new tools, processes, assumptions, and modes of operation.