

The first three signals are the only ones you can influence directly. The user’s demographic information and location.What the user has searched for in the past.How recently the user watched a video about this topic.How many videos the user has watched from your channel.Watch time (the combined amount of time that viewers spend watching your videos).Click-through rate (the likelihood of someone clicking on your video after seeing it).In this research paper published by Google engineers Paul Covington, Jay Adams, and Emre Sargin, they break down the signals they use to rank videos for YouTube recommendations:

If you want to get more video views in the long term, you need to understand a few things about how the YouTube algorithm works in 2019. While these contribute to the discovery of your videos, alone they don't unlock the lion's share of views you stand to gain from YouTube's recommendation engine (via YouTube's homepage and “recommended for you” suggestions). Much of the discussion about getting views on YouTube focuses on YouTube SEO, social media promotion, and getting subscribers. While it didn’t garner much attention at the time, it bears a lot of relevance to the YouTube of today since, according to YouTube’s Chief Product Officer, 70% of YouTube views now come through this recommendation engine. In a research paper published in 2016, a group of Google engineers shared their plans for how videos could be surfaced through YouTube’s recommendation engine for a better user experience. It’s one of the platform’s most carefully guarded secrets, after all.

They believe there’s no understanding how the YouTube algorithm works. Many video creators, whether professional YouTubers or brands on YouTube, regard the YouTube algorithm as a complete mystery-a higher power that rules over their view counts, completely outside of their control.
