Number of adults using social networks quadrupled since 2005

Whereas once teenagers and college students were the denizens of social networking sites, their parents and grandparents are now getting in on the act. In fact, Pew's recent research found that adult use of social networking sites has quadrupled since 2005. Now, 35% of U.S. adults who use the Internet have a profile on at least one social network such as Facebook, MySpace, or Twitter.

Facebook, the number one social networking site with over 150 million users, experienced a 276% rise in its 35-54 year old demographic in the last six months alone.

But teenagers remain the most likely demographic to use social networking sites, albeit with a slowing growth in uptake. Seventy-five percent of online adults aged 18-24 have a social network profile, as do 57% of online adults aged 25-34. Profile ownership drops to 30% among 35-44 year olds, 19% among 45-54 year olds, 10% among 55-64 year olds and 7% of online adults 65 and older.

Most adults (90%) use social networking sites to stay in touch with people they already know, while 49% of both teenagers and adults are looking to make new friendships, found Pew's research. Similarly, adults are most likely to restrict access to their profiles (60%) so that only their friends can see it, and 58% restrict access to certain content within their profile.

Tags: adults, demographic, Facebook, Pew, social network, social networking, teenagers