WhatsApp lets users send text messages, audio messages, videos, and photos to one or many people with no message limits or fees.
What parents need to know
It's for users 16 and over. Lots of younger teens seem to be using the app, but this age minimum has been set by WhatsApp.
It can be pushy. After you sign up, it automatically connects you to all the people in your address book who also are using WhatsApp. It also encourages you to add friends who haven't signed up yet.