You can follow accounts, and they offer a Following tab to keep track of accounts you really like, but the default consumption mode is to use it just like TV. When you're done with a video you scroll to the next. The app uses signals like how long you spent on a video, whether you liked it or not, whether you sent it to friends or not, etc to see how much you like a video. You can also reset your "algorithm" if you find yourself consuming content you don't like.