Social Networking Websites and Teens: An Overview (Pew Internet & American Life Project)
A social networking site is an online place where a user can create a profile and build a personal network that connects him or her to other users. In the past five years, such sites have rocketed from a niche activity into a phenomenon that engages tens of millions of internet users. More than half (55%) of all online American youths ages 12-17 use online social networking sites, according to a new national survey of teenagers conducted by the Pew Internet & American Life Project. The survey also finds that older teens, particularly girls, are more likely to use these sites. For girls, social networking sites are primarily places to reinforce pre-existing friendships; for boys, the networks also provide opportunities for flirting and making new friends.
http://www.pewinternet.org/PPF/r/198/report_display.asp