A social network service focuses on building and reflecting of social networks or social relations among people, e.g., who share interests and/or activities. A social network service essentially consists of a representation of each user (often a profile), his/her social links, and a variety of additional services. Most social network services are web based and provides means for users to interact over the internet, such as e-mail and instant messaging. Although online community services are sometimes considered as a social network service in a broader sense, social network service usually means an individual-centered service whereas online community services are group-centered.
The main types of social networking services are those which contain category places (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, Bebo and Twitter widely used worldwide; MySpace and LinkedIn being the most widely used in North America;[1] Nexopia (mostly in Canada);[2] Bebo,[3] Hi5, StudiVZ (mostly in Germany), iWiW (mostly in Hungary), Tuenti (mostly in Spain), Decayenne, Tagged, XING;[4], Badoo[5] and Skyrock in parts of Europe;[6] Orkut and Hi5 in South America and Central America;[7] and Friendster, Mixi, Multiply, Orkut, Wretch, Xiaonei and Cyworld in Asia and the Pacific Islands and Orkut and Facebook in India.