So where else are young people going online? And who are they talking to?
If you believe media reports, Facebook has gone out of favor with the younger demos, ages 14 - 34.
But a recent survey, reported this week by Adweek, shows that 66 percent of people ages 14 - 34 are frequent users of FB. What's changing is that they're increasingly using other platforms as well -- mainly YouTube.
Another study, meanwhile, shows that nearly two-thirds of young people have joined at least one social network by the time they're 10 years old. The survey, by the London School of Economics, found that 28 percent of British kids ages 9 and 10 already have a personal profile on a social network -- mostly Facebook. That number has more than doubled over the past year and a half.
The U.S. has restrictions on how marketers interact online with kids under 13 -- basically, they can't. And although many parents restrict (or try) what their kids can do online, the growing access to mobile devices makes parental control ever more challenging. Once a kid has a social network profile, he or she becomes a target for sometimes questionable people -- scammers or, worse yet, pedophiles.
There's a TV station in New York that for years has been asking this question at the start of the 10 p.m. newscast -- "It's 10 p.m. Do you know where your children are?"
The challenge these days is more like, "It's any time during the day. Do you know what your children are doing online and who they're talking to?"