A user of a Social Network Site can add other profiles to the friends list on their profile. Usually a friend  connection has to be requested and confirmed by both parties. Once created, it is possible to view an individuals list of friends from their profile on the Social Network Site. social network sites Many Social Network Sites will indicate to a logged in user whether they have friends in common with the individual whose profile they are viewing.

Social network is popular market in the internet industry now, I think this is fueled by Facebook success story.