All Links Are Social
By the broad “inter-” meaning of “social,” all link types together are the complete list of “relevant” ties between any two nodes (people, positions, groups, organizations, places). Social networks, then, are inherent in the articulation of any and all link types. The patterning of this totality of links represents the impact of individual links on individual nodes, but the measures of impact come from the context of the whole pattern of links. Network measures are all relative.
Social Networks
After decades of labor at the fringes of science, social network analysis (see INSNA) has come into its own in the Internet Age. Our focus on the network of positions of an organization complements the great work being done to understand social networks. Indeed, we expect that many of the tools and measures of SNA will be regularly applied to the fleshed out working networks of people doing their job.

Wikipedia offers a good summary of social networks in the broadest terms:

"A social network is a social structure made of nodes (which are generally individuals or organizations) that are tied by one or more specific types of relations, such as values, visions, idea, financial exchange, friends, kinship, dislike, trade, web links, sexual relations, disease transmission (epidemiology), or airline routes."