1) Facebook, enables its users to present themselves in an online profile, accumulate "friends" who can post comments on each other's pages, and view each other's profiles. Facebook members can also join virtual groups based on common interests, see what classes they have in common, and learn each others' hobbies, interests, musical tastes, and romantic relationship status through the profiles.
2) Facebook constitutes a rich site for researchers interested in the affordances of social networks due to its heavy usage patterns and technological capacities that bridge online and offline connections.
3)facebook support both the maintenance of existing social ties and the formation of new connections
4)Facebook allows users to connect with people they know and meet new friends