TikTok explains how the recommendation system behind its ‘For You’ feed works

Open up short-form video app TikTok and you’re met with a stream of popular videos, tailored to your own interests. But when your friend launches TikTok on their own phone, they’ll see something different. TikTok calls this main stream of content the “For You” feed because of how it’s personalized to the individual user. But how the recommendation system worked behind the scenes was something of an unknown — until now. Today, the company detailed the factors that contribute to the For You feed, as well as how they’re weighted for each individual user.
It also explains what it’s doing to ensure the system isn’t creating filter bubbles — that is, a feed where you’re presented with a homogeneous stream of videos.
Like many recommendation systems, TikTok’s For You feed is powered by user input.