A social network exists wherever people interact. Your ward activity, the high school football game, the family reunion, and your bowling league are all social networks. They may vary in intimacy, group size, or degree of connectedness. The Oxford English Dictionary defines social network as “a system of social interactions and relationships; a group of people who are socially connected to one another.” The genius of social networking online is the facilitation of activities that have always been part of the human social experience, coupled with a massively interconnected network infrastructure. When you do that really well, it pops out the other side as Facebook.

Today, of course, when you say “social networking” people immediately think of any number of websites that provide the means to establish and maintain connections with friends and acquaintances. Social networking sites facilitate the creation and maintenance of online communities. These communities may mirror analogous communities that exist in the real world. For example, an extended family may meet in person for a family reunion every year or two, but may also create a Facebook group to facilitate communication, planning, and sharing in between reunions. An online community may also exist without an analogous offline community. Many open source software development projects involve software developers from around the world who have never actually met in person but who collaborate online to develop software products that support their mutual professional needs.

While a rich variety of social networking sites exist to serve a diverse set of needs, in this chapter we’ll focus primarily on social networks that fit the following definition: “a web-based service that allows individuals to (a) construct a public or semi-public profile within a bounded system, (b) articulate a list of other users with whom they share a connection, and (c) view and traverse their list of connections and those made by others within the system.”¹