Age Rating:  13+

Musical.ly is a performance- and video-sharing social network that mostly features teens lip-synching to famous songs but also includes some original songwriting and singing. "Musers," as devoted users are called, can build up a following among friends or share posts publicly.

Why It's Dangerous  – Songs and videos contain lots of questionable content. Because the platform features popular music and a mix of teen and adult users, swearing and sexual content are commonplace.

Gaining followers and fans feels important. Teens want a public profile to get exposure and approval, and many are highly motivated to get more followers and likes for their videos.

The app also encourages in-app messaging and has been linked to unwanted sexual advances and threats on young children.