What’s both crucial and easy to miss about TikTok is how it has stepped over the midpoint between the familiar self-directed feed and an experience based first on algorithmic observation and inference. The most obvious clue is right there when you open the app: the first thing you see isn’t a feed of your friends, but a page called “For You.” It’s an algorithmic feed based on videos you’ve interacted with, or even just watched. It never runs out of material. It is not, unless you train it to be, full of people you know, or things you’ve explicitly told it you want to see. It’s full of things that you seem to have demonstrated you want to watch, no matter what you actually say you want to watch.