Online social networks

The popularity and complexity of online social networks (OSNs) continues to grow unabatedly with the most popular applications featuring hundreds of millions of active users. Ranging from social communities and discussion groups, to recommendation engines, tagging systems, mobile social networks, games, and virtual worlds, OSN applications have not only shifted the focus of application developers to the human factor, but have also transformed traditional application paradigms such as the way users communicate and navigate in the Internet. Indeed, understanding user behavior is now an integral part of online services and applications, with system and algorithm design becoming in effect user-centric. As expected, this paradigm shift has not left the research community unaffected, triggering intense research interest in the analysis of the structure and properties of online communities.