A social networking site located at facebook.com.
Facebook is the largest social networking site in the world, with 750+ million active users as of July 2011. Marketers are increasingly paying attention to Facebook since the audience is so large and engaged.
Marketers can reach people by direct Facebook advertising or by non-advertising avenues (social media marketing and/or content marketing).
Advertising on Facebook, like on most social network sites, is known for having a very low CTR. But as long as ads are CPC, i.e. payment based only on clicks, CTR is not relevant to ROI. On the plus side, Facebook has powerful targeting options such as location, language, likes and interests, connections, demographics and advanced demographics. The better the targeting options, the more opportunity to test and improve.
see also: Social Media Tools
Infographic: The History of Advertising on Facebook
Mashable (June 28, 2011)
7 Facebook Marketing Tips From World’s Top Pros
Social Media Examiner (August 24, 2010)
Facebook Marketing: Ultimate Guide
SEO Moz (July 14, 2010)