They help you unlock more ranks and classes. When you post and interact with the community, you get xp, the more xp you have, the higher your level. If you hover over a member's name, you will the that member's rank and class under their level number. For example, my rank is 'Artisan' and my class is 'Musician'. These ranks and classes don't really do anything other than show what members are more active on the site. The higher level you have, the more classes you can choose from. for a list of classes and at what level they unlock at, click this link https://www.planetminecraft.com/members/levels/
