Half of US adults are using social networks such as Facebook, Myspace or LinkedIn, according to a survey published Friday.

The survey by the Pew Research Center's Internet and American Life Project found that 65 percent of adult Internet users in the United States use social networks.

That translates into 50 percent of the entire US adult population, Pew said.

Just eight percent of Internet users used social networks in 2005, according to the Washington-based Pew.

"Social networking sites continue to cement their place as a significant part of mainstream online life," said Kathryn Zickuhr, a co-author of the report.

The survey found that social networks are more popular among women with 69 percent of online women visiting social networks compared to 60 percent of men.

Pew said social network use is most prevalent among the young but 33 percent of adult Internet users aged 65 and older now use the sites, up from 26 percent a year ago.

"The graying of social networking sites continues, but the oldest users are still far less likely to be making regular use of these tools," said Mary Madden, a co-author of the report.

Pew said 83 percent of US Internet users between the ages of 18 and 29 use social networks, 70 percent of 30 to 49 year olds, 51 percent of 50 to 64 year olds and 33 percent of those aged 65 and older.

Forty-three percent of online adults visit a social network on a typical day, Pew said, making only email and using a search engine more frequent daily online activities.

Sixty-one percent of adult Internet users use email on a typical day and 59 percent use a search engine.

The survey of 2,277 US adults was conducted between April 26 and May 22 and has a margin of error of plus or minus 2.4 percentage points.