The document discusses social media, social networks, and social network services. It begins by distinguishing between social networks, which are social structures composed of interconnected individuals or groups, and social network services, which allow individuals to construct public profiles, connect with other users, and view their connections. It then defines social media as internet-based applications that allow the creation and sharing of user-generated content. The document provides several examples of social media platforms and concludes with recommendations on engaging audiences and some dos and don'ts for using social media in marketing.