What should I use it for?
In case of posts - should I downvote things that I don’t agree with? Or things that I don’t want to see in my feed (posts with low amount of votes fell more to the bottom)? Or things that I consider harmful/stupid/younameit?
In case of comments - should I downvote something that I don’t agree with? When should I use this button in case of comments. Or maybe I should not - cause what’s the point, actually?
Individual communities are free to ask that the buttons be used a certain way, but the ecosystem in general isn’t prescriptive about it. Right now it isn’t super important because everything’s slow enough you can see most things. In general, I’d advocate to at least upvote things you’re glad you saw/read.