About : 

Social media, a form of mass media communications on the Internet (such as on websites for social networking and microblogging) through which users share information, ideas, personal messages, and other content (such as videos). 

The earliest forms of social media appeared almost as soon as technology could support them. E-mail and chat programs debuted in the early 1970s, but persistent communities did not surface until the creation of the discussion group network USENET in 1979.  

The first companies to create social networks based on web technology were Classmates.com and SixDegrees.com. Classmates.com, founded in 1995, used an aggressive pop-up advertising campaign to draw web surfers to its sites .