The power, impact, and importance of social media is evident through its usage statistics, as shown in Table 1, provided by the Nielsen Company (2010), showing average usage times and the number of monthly unique visitors to social networking sites.
Table 1. Unique visitors to social networking sites in December 2009 (in millions)
| Country | Unique Audience (000) | Time per Person (hh:mm:ss) |
| United States | 142,052 | 6:09:13 |
| Japan | 46,558 | 2:50:21 |
| Brazil | 31,345 | 4:33:10 |
| United Kingdom | 29,129 | 6:07:54 |
| Germany | 28,057 | 4:11:45 |
| France | 26,786 | 4:04:39 |
| Spain | 19,456 | 5:30:55 |
| Italy | 18,256 | 6:00:07 |
| Australia | 9,895 | 6:52:28 |
| Switzerland | 2,451 | 3:54:34 |
| Source: The Nielsen Company, 2010 |
However, even though social media is such a widespread and active phenomenon, it does not have any one commonly accepted definition. We found numerous authors using a variety of semantics to define social media. Studies have taken the construct to be everything from “user generated content” (Castillo, Donato, Gionis, & Mishne, 2008, p. 1) to “media with possibilities of relationships” (Gilbert & Karahalios, 2009, p. 1) with no real semantic consensus or exact agreement upon what is and what is not considered social media. One major reason behind this definitional uncertainty is the arrival of new technologies almost every year. These new technologies not only introduce new forums and avenues of usage, but also serve to update and evolve existing traditional technologies and applications into having social media components. As an example, computer games, online news articles, online company and product sites and many other applications that were originally considered to be traditional, i.e. non-social online media, have in recent years been taken under the wing of social media with the addition of comment boards, online gaming communities, fan blogs and other tools opening the way for social interaction. Social scientists and researchers have reacted to this evolving technology by continuously widening their definitions of it (Social Media Defined, 2007), more recently including tools by name like wikis, blogs, social networking platforms, and others (Xiang & Gretzel, 2009). The element of connectivity is the recurring theme within most definitions, the social aspect of the communication, however, is open for interpretation.
In this chapter, we define social media as any private or public network based application that allows the exchange of information and social interaction between two or more individuals. The information may be live or synchronous (e.g. instant messaging), or linear time gapped or asynchronous (such as bulletin boards and wikis). The tools that qualify as social media must allow two-way communication between the initiator of the conversation and intended partners, or the author of the information and his audience. Whether the audience/partners choose to reply or comment in turn does not have a bearing on the qualification of the exchange as a social media message.