Not to be confused with classes.
Classes determine your character's combat level
Ranks determine your characters social rank
Social ranks can be earned through services to the site, accomplishing acts of great valour, or simply by survivng over time and proving your worth.
For some things, such as shop ownership, you'll need ranks.
Otherwise, they're just a mod to keep you interested in the game
The different ranks are:
Commoner
Low Nobility
Noble
High Noble
Lord
