Unless you live with a teenager, you've probably never heard of Musical.ly.
If you do, then you've probably already appeared in one of your kid's music videos.
The DIY music video app first came on the scene in 2014, but exploded to the top of the App Store charts last summer. It hasn't fallen below the top 40 since. Often, it's swapping top places in the app store with Snapchat and Instagram.
The 15-second videos are typically people lip-syncing or dancing to some of the top hits. More recently, Musical.ly stars have started launching their own careers, and traditional music stars, like Jason DeRulo, are now pledging to debut their videos on the platform first, a coup over YouTube.
Today, more than 10 million people use the app daily and produce around the same number of videos every single day. All in, 70 million people have registered as Musical.ly users, says its cofounder and co-CEO Alex Zhu.