Social Media sites are characterized by the sharing of information between users within a defined network. They include social networking sites like LinkedIn, Facebook, mySpace and Twitter or social bookmarking sites like Del.icio.us, social news sites like Digg or Reddit, and other sites that are centered on user interaction. Social Media allow the initiation of conversation by either party. The size of the network is a reflection of the active participation of the audience, as consumer-generated media represents that vast majority of all content. For consumers the true value of a network is measured by the frequency of engagement of the participants. For marketers, endorsement by consumers in the form of friending/following/subscribing validates their efforts and activates a viral distribution of their brand across channels.