there actually are quite a few threads on reputation. You can give reputation to other people, and they can give it to you. For example, if I were to rep you, you would receive 18 rep points because I have 18 powers. For every 100 rep points you get, you receive a power and a green bar. When you have made 50 posts, you receive a power. The mods predetermine the number of posts you need to make to get your next power. For myself, every 1000 posts I make, I receive a power. You can only rep the same person a couple of times before a pop-up tells you that you must spread rep around before giving it to that person again.