Question about up and down

I notice that in the support forum, there are these up and downs. What are they? who put them there and why are they there? See the screenshot.

 

You mean Unity Answers. That's not forum. It's important, because this is the forums.
Example: https://answers.unity.com/questions/1662157/is-there-an-easy-way-to-save-custom-binary-files-t.html

The up and down means you can upvote or downvote (like/dislike basically) content (questions and answers).
More information in the FAQ (Karma/Reputation section).

 

ok thank you.