Social networks have existed for friendship, business and other reasons long before online groups were created. The Freemasons are thought to have originated in the Middle Ages. Boyd and Ellison (2007) assert that Community Memory was the first computerised bulletin board community in 1973 . Bulletin boards were largely replaced by web based Internet Forums; many of which have been superseded by the social network systems ubiquitous today.

Boyd and Ellison define Social Network Sites (SNS) as

” … web-based services that allow individuals to

(1) construct a public or semi-public profile within a bounded system,

(2) articulate a list of other users with whom they share a connection, and

(3) view and traverse their list of connections and those made by others within the system. The nature and nomenclature of these connections may vary from site to site.”

Typically:

• SNS allow users to make their social networks public
• large SNS enable users to maintain their connections with offline groups
• users can contact new people via a shared third party connection with offline connections to both parties
• user profiles are included
• bidirectional confirmation of ‘friendship’ is required (eg Facebook)
• some (such as Twitter) allow unidirectional ‘followers’ or ‘fans’
• public messages can be posted on friend’s profiles
• private messages are allowed between friends
• initially SNS often attract homogeneous groups
• some SNS are deliberately exclusive

Popular SNS in 2017 include Facebook, Twitter, and LinkedIn. Britizen is a conceptual design for a SNS who primary purpose is to influence British society.

Reference

Boyd, D.M., Ellison, N.B., 2007. Social Network Sites: Definition, History, and Scholarship. J. Comput. Commun. 13, 210–230. doi:10.1111/j.1083-6101.2007.00393.x