Facebook

A social networking site founded in 2004 by Mark Zuckerberg. It initially targeted Harvard students, but was later opened to other universities and then high schools. In 2006, Facebook allowed everyone to join and also added a News Feed feature that would broadcast changes in members' pages to all Facebook users identified in their personal network of friends. It turned Facebook into a personalized social news service.

The name of the site comes from the paper document often issued to college freshmen to help them get acquainted on campus.

Facebook Platform
In 2007, Facebook introduced its application platform to software developers. Within a few months, thousands of programs were available for enhancing a Facebook page in myriad ways such as sharing certain Facebook information with selected friends as well as collecting and sharing multimedia, humor, games, sports, blogs and classifieds. See Facebook Platform.

Facebook Beacon Social Ads
In late 2007, Facebook introduced its Beacon social advertising program, which tracks Facebook users who visit the advertisers' sites. Ads are then targeted to the friends of these users indicating that their friend has taken some action such as purchasing a product, renting a video or signing up for a service. The system was launched as an opt-out service in the beginning, causing enormous controversy. It was later changed to opt-in. See social networking site, social advertising, opt-in and opt-out.