A social network service uses software to build online social networks for communities of people who share interests and activities or who are interested in exploring the interests and activities of others.
Most services are primarily web based and provide a collection of various ways for users to interact, such as chat, messaging, email, video, voice chat, file sharing, blogging, discussion groups, and so on. Social networking has revolutionized the way we communicate and share information with one another in today's society. Various social networking websites are being used by millions of people everyday on a regular basis and it now seems that social networking is a part of everyday life.
The main types of social networking services are those which contain directories of some categories (such as former classmates), means to connect with friends (usually with self-description pages), and recommender systems linked to trust. Popular methods now combine many of these, with MySpace and Facebook being the most widely used in North America, Bebo, MySpace, Skyrock Blog , Facebook and Hi5 in parts of Europe,, Orkut and Hi5 in South America and Central America, Friendster, Orkut and CyWorld in Asia and the Pacific Islands. Le Monde provided a detailed map of popularity, January 14, 2008. 
There have been some attempts to standardize these services to avoid the need to duplicate entries of friends and interests(see the FOAF standard and the Open Source Initiative), but this has led to some concerns about privacy.