Shorts & Vertical Video
Shorts algorithm
Also called: Shorts recommendation system
Shorts are served by swipe, so the system ranking them faces a different problem from the one filling the home page. YouTube split short-form and long-form watch history into separate signals after early Shorts viewing started pushing long-form out of people's recommendations. Retention signals carry consistent weight here, because every Short has an average view duration and a viewed-versus-swiped-away figure, while likes, comments and shares exist on only some of them. That is why the opening seconds attract so much attention. The swipe decision happens there, before anything else in the video has had a chance to count for anything.