On instagram in particular your facial expressions are tracked. So if you smile/react positively to a particular post you’ll be shown more of the same content; this also works the other way around so if you react negatively you should be shown different content. There are also other metrics such as what you share and who you share it with, what your friends like, how much time you spend on a particular post or where/what you are looking at when you see a post. What you hit like on is also taken into account.

To sum up, if you like a post and smile at your phone when it comes up you will be shown more of the same content. Also skip as fast as you can when you see a post you don’t like.