Adults do it; teens do it; kids do it, too.
Which brings up the question: How young is too young to be on Facebook and other social networking sites?
The magic number is 13, says Amanda Lenhart with the Pew Research Center's Internet and American Life Project. That's the minimum age requirement, in theory, for young people to sign up on most of the social networking sites.
As it turns out, however, controlling children's online activities or even knowing when they're mature enough to manage their own accounts is more complicated than it sounds.