This is my first question, so feel free to edit. I am open to suggestions.
Oh! I am so excited!! This is my first puzzle!
I can show you where the things are. Ready for a quick game?
I am rich you know! I can be usually in a command, or a hat.
I am famous; I am in maths; I am the sun.
Open me... close me, you will get less or more.
Guessed it yet? I think it's worth trying for!
Each line represents something. Combining all those things gives you the answer. But the final line is just for the rhyme (I know it's not a good one, but I tried).
It is related to something, every member on every Stack Exchange site uses.