Thirty-five percent of the Americans 65 years old or older now use social networking sites, said Lee Rainie, founder and director of the Pew Research Center's Internet & American Life Project, during a video conference on June 20.

According to a recent survey by the Pew Internet Project, two-thirds of Internet users -- half of all Americans  -- use social networking sites.

Interestingly, the population of social networking sites is aging as more oldsters jump on the bandwagon. "It is not just an area that young people enjoy participating in," said Rainie.

According to the survey, 66 percent of Internet users use Facebook and social networking sites. Fifteen percent use Twitter.

For Twitter, the population is getting younger. "At the beginning, Twitter was something that people in their 30s or their 40s were using. Now it's 20-year-olds and even teenagers who are becoming a little bit more interested," he added.

The results in this survey are based on data from telephone interviews conducted by Princeton Survey Research Associates International from January 20 to February 19, 2012, among a sample of 2,253 adults aged 18 or older.

The Pew Internet project is a non-profit, non-partisan "fact tank" that studies the social impact and evaluates the evolving role of the Internet in modern political campaigning as candidates and voters use technology to connect to the debate, raise money, and mobilize support.

Rainie and co-author Barry Wellman wrote Networked: The New Social Operating System. Rainie also contributed to a series of books about the future of the Internet. Prior to launching the Pew Internet Project, Lee was managing editor of U.S. News & World Report.

(Reporting from New York City)