What is Tik Tok (and why)?

TikTok is an app for making and sharing short videos. The videos are tall, not square, like on Snapchat or Instagram’s stories, but you navigate through videos by scrolling up and down, like a feed, not by tapping or swiping side to side.  You may not want to be part of it, but you need to know what it is and how it is (not) regulated.