Parents need to know that WhatsApp Messenger lets users send encrypted text messages, videos, photos, and audio messages to one or many people with no message limits or fees( until after the first year of use, when there’s a$0.99 annual fee) . The catch is these messages can only be sent to other smartphone users who also have WhatsApp. Once you install the app, it checks your address book to see if anyone else you know is already using WhatsApp and connects you automatically. The app also suggests allowing messages to be sent from your phone to those in your address book who aren’t yet using WhatsApp, encouraging them to sign up. WhatsApp’s license agreement requires users to be age 16 or older. In terms of questionable content, it’s completely up to the user, but location-sharing capabilities make this app most appropriate for older teens.