Social networking is not a new concept. Various traditional facets of our existence might be reinterpreted as social networking, from early Christians to the World Wide Web. It refers to the act of relating nodes for example; individuals, organisations, other social entities through social links for example; friendship, professional relationship, information exchange. Before the 20th century, social networking could only take place at short distance, or with considerable time delay when travelling or exchanging letters. Since the 1950’s, telephones, tele- and videoconferencing have allowed real-time communications even over long distances. These two-way communication channels are generally good links for pairs of people or small groups, but they tend to be inefficient for large-scale, mass interactions. Moreover they enable simultaneous communications. This book provides leading edge research on this field from around the globe.