WASHINGTON (AP) -- Relieved your kids aren't posting embarrassing messages and goofy self-portraits on Facebook?
They're probably doing it on Instagram and Snapchat instead.
The number of popular social media sites available on kids' mobile devices has exploded in recent years.
The smartest apps now enable kids to chat informally with select groups of friends without bumping up against texting limits and without being monitored by parents, coaches and college admissions officers -- who all are frequent Facebook posters themselves.
Many of the new mobile apps don't require a cellphone or a credit card. They're free and can be used on popular portable devices such as the iPod Touch and Kindle Fire, as long as there's a wireless Internet connection.