[AChimp]

A pretige class is a class that you can acquire levels in, but must meet the prerequisites in your base class(es) first (usually stuff like must be at least level 5, 3 points in Listen, etc.)

Some require you to have done certain things, like gain the respect of a particular order (this is particularly true for fighter pretige classes, which usually mean you become a Knight of Whatever). Others are based on race and your base classes.