58% of All U.S. Web Users Visit Social Networking Sites

As popular as social networking has proven to be--eMarketer now says 58 percent of U.S. Internet users visit a social networking site at least once a month--there have been questions about Facebook's business model. The answer typically has been that "a model will be found," as improbably as was the case for Google before it.

Advertising and e-commerce have been the most-frequent answers to the question of how any widely-used "free to use" application can support itself over time. And despite some "privacy" stumbles of late, Facebook continues to explore ways to position itself as an advertising venue, despite some obstacles, related in part to fragmented use of the service (there is no single "home page" everybody goes to, which would create a huge venue for display ads) and the suitability of the content environment (YouTube has the same basic problem).

Still, the rule in media is that whenever a sufficient number of "eyeballs" can be aggregated, advertising becomes viable.

eMarketer estimates that 57.5 percent of Internet users, or 127 million people, will use a social network at least once a month in 2010. That's eyeballs.

Two-Thirds of Web Users to Visit Soc Nets in 2014 - eMarketer