Social Media is the evolution of the concept of Mass Media that places more emphasis on global coverage being a more traditional concept. Social Media changes radically in terms of information management, as web 2.0 users happen to have an active role and stop being mere readers of content becoming content generators, thus also become emitters message.
When before had an editor who decided which were interesting contendios, they are now the same users who decide, spread themselves virally “word of mouth” as more or less interesting. This spread is by recommendations through social networks, blogs or publishing of the content in new places. Now anyone can link the content area in seconds on your social network with just click on the buttons recommendation or to share.