Question about User Levels/Promotion

Hello, I’m wondering if someone can explain the levels of User Promotion from 1 to 10? I have many registered users, but not sure what each level or promotion will allow to each user? Everyone is currently at 0, so it shows ‘Promote’ next to their name. My site only allows me to post which is how I want it. But I would like to know more about this so I can better understand. Thanks.