Ask HN: What is the "Like" in a context of social network web-sites?

I teach math to a group of young kids who are too young to be introduced to a smartphone. They asked me what a "Like" is. I told them about the concept of "Internet Points", but I feel like I'm missing something, for example how likes affect the algorithmic feed (but there is a big chance they do not know what is the feed as well).

For example, HN has more than 1 kind of like: an upvote, a vote for the submission, and vouch action. But do you have a logic when to use them on HN and on other resources? Are there websites where "liking" something has a noticeable impact on the feed?