Meta is introducing Teen Accounts to Facebook and Messenger in the U.S., U.K., Australia, and Canada. The feature enrolls young users into an app experience with built-in protections. Teens will only receive messages from people they follow or have messaged before, and only their friends can see and reply to their stories. They will also receive reminders to leave the social networks after an hour a day and be enrolled into "Quiet mode" overnight. Teens under 16 need parental permission to turn off the app's feature that blurs images containing suspected nudity in DMs.