More than half of US adults use Facebook: study

More than half of US adults use online social networking service Facebook, according to an upcoming study.

A report by Edison Research and Arbitron Inc. to be released on April 5 includes the finding that 51 percent of US residents age 12 or older have profiles set up at Facebook.

Facebook terms of service require people to be at least 13 years old to be members of the online community, which boasts more than a half-billion users.

"We have been tracking the growth of Facebook since 2008, and have watched it go from eight percent usage just three years ago, to 51 percent today," New Jersey-based Edison said in a release.

The market tracking firms based the findings on a January survey of 2,020 people. Study findings presented in a webcast will include the popularity of accessing social networks using mobile phones, according to Edison.