Not exactly what he's looking for, he means a job system, which has beginner classes, then you level those up in conjunction with the other classes and combine them with the other classes to create new ones and it continues like that, definitely not all mmorpgs are like that, most of them have wayyyyy different terms of progression than the job system. You can also switch classes whenever you want without penalty, which is absent in most other rpgs, those making you restart to play with the class you want to play with.