Traditionally, the level of players has been defined using "kyu" and "dan" ranks. Kyu ranks are considered "student" ranks. Dan ranks are considered "master" ranks. Beginners who have just learned the rules of the game are usually around 30th kyu. As they progress, they advance numerically downwards through the kyu grades. The best kyu grade attainable is therefore 1st kyu. If players progress beyond 1st kyu, they will receive the rank of 1st dan, and from thereon will move numerically upwards through the dan ranks. In martial arts, 1st dan is the equivalent of a black belt. The very best players may achieve a "professional dan rank".