On TikTok everything revolves around “sounds”. Sounds are little clips of audio, usually between 15 and 60 seconds long, which can range from music to tv shows to clips of conversations, that are overlaid on top of your TikTok video. When you record on TikTok you can first choose the sound you want to use and then as you hold down the record button the app will play the sound so you can lip synch, dance, or further choreograph your video to the words and beat of the sound.”
https://medium.com/@mattprd/how-tiktok-is-changing-the-world-and-youre-missing-it-fa283338649a