Social media are computer-mediated tools that allow people to create, share or exchange information, ideas, and pictures/videos invirtual communities and networks. Social media is defined as "a group of Internet-based applications that build on the ideological and technological foundations of Web 2.0, and that allow the creation and exchange of user-generated content." Furthermore, social media depend on mobile and web-based technologies to create highly interactive platforms through which individuals and communities share, co-create, discuss, and modify user-generated content. They introduce substantial and pervasive changes to communication between businesses,organizations, communities, and individuals. These changes are the focus of the emerging field of technoself studies.
Social-media technologies take on many different forms including magazines, Internet forums, weblogs, social blogs, microblogging, wikis, social networks, podcasts, photographs or pictures, video, rating and social bookmarking. Technologies include blogging, picture-sharing, vlogs, wall-posting, music-sharing, crowdsourcing and voice over IP, to name a few. Social network aggregation can integrate many of the platforms in use.
Some social-media sites have greater virality - defined as a greater likelihood that users will reshare content posted (by another user) to their social network. Many social-media sites provide specific functionality to help users reshare content - for example, Twitter's retweet button, Pinterest pin orTumblr's reblog function. Businesses may have a particular interest in viral marketing; nonprofit organisations and activists may have similar interests in virality.