The dan ranking system is used by many Japanese, Okinawan, Korean, and other martial arts organizations to indicate the level of a person's ability within a given system. Used as a ranking system to quantify skill level in a specific domain, it was originally used at a Go school during the Edo period. It is now also used in most modern Japanese fine and martial arts.

In East Asian martial arts, the black belt is associated with expertise, but may indicate only competence, depending on the martial art. The use of colored belts is a relatively recent invention dating from the 1880s.