A social network service focuses on building online communities of people who share interests and/or activities, or who are interested in exploring the interests and activities of others. Most social network services are web based and provide a variety of ways for users to interact, such as e-mail andinstant messaging services.
The main types of social networking services are those which contain category divisions (such as former school-year or classmates), means to connect with friends (usually with self-description pages) and a recommendation system linked to trust. Popular methods now combine many of these, with Facebook and Twitter widely used worldwide; MySpace and LinkedIn being the most widely used in North America;[1] Nexopia (mostly inCanada);[2] Bebo,[3] Hi5, StudiVZ (mostly in Germany), iWiW (mostly in Hungary), Tuenti (mostly in Spain), Decayenne, Tagged, XING;[4], Badoo[5] andSkyrock in parts of Europe;[6] Orkut and Hi5 in South America and Central America;[7] and Friendster, Mixi, Multiply, Orkut, Wretch, Xiaonei andCyworld in Asia and the Pacific Islands and Orkut and Facebook in India.
via wikipedia
