What do all the icons on the forum mean?

[finall]

Maybe not the right place to post this, but I can't seem to find a "general questions" forum on this website. Is there one, and if so, maybe a moderator could move this post please.

I need to ask:
What does the "reputation" icon do in posts? Does clicking it give the post-er add good reputation or bad reputation?

Is there a legend that explains this and other symbols (e.g. what defines a "bad post") somewhere on this forum? I could not find it...