1) Complex systems theory 2) Facebook 3) Sociological terminology 
[sociolinguistics] In the field of sociolinguistics, social network is a term used to describe the structure of a particular speech community. Social networks are composed of a `web of ties` (Lesley Milroy) between individuals, and the structure of a network will vary depending on the types of connections it is composed of. Social network t... A social network is a social structure made up of a set of social actors (such as individuals or organizations) and a set of the dyadic ties between these actors. The social network perspective provides a set of methods for analyzing the structure of whole social entities as well as a variety of theories explaining the patterns observed in these s...
a web of social ties that links people who identify with one another