Social Media, or Social Network, is a generic expression that indicates technologies and practices on the Net that people adopt to share textual content, images, audio and video. Professors Andreas Kaplan and Michael Haenlein defined social media as a group of web applications based on the ideological and technological assumptions of Web 2.0. that enable the creation and exchange of user-generated content.
Social media fundamentally represents a change in the way people read; learns and shares information and content. With social media, the typical communication model of traditional media (radio, press, television) changes radically; the message is no longer of the "one to many" type (ie mainly one-way, from the broadcaster to its audience), but of the "peer" type; multiple broadcasters, high level of interaction. This change in the communication model can lead to a democratization of information, transforming people from "mere" content users to publishers themselves. Social media has become very popular because it allows people to use the web to establish personal or business relationships. They are also defined user-generated content (UGC) or consumer-generated media (CGM).