The black belt to signify a "dan" rank, denoting mastery or advanced skill, was introduced in the modern martial art Judo by Jigoro Kano. It is to differentiate from a beginner or student rank known as a "kyu" rank in Judo, which is often denoted by wearing a white belt or other colored belt.

The tradition of awarding students a black belt to signify mastery has spread to other Japanese-derived martial arts such as BJJ and Karate, but has spread to even non-Japanese traditions through some Kung fu schools awarding their students a black sash to denote mastery, or a black belt in Korean martial arts such as Tae Kwon Do.

The term "black belt" has also become a modern buzzword with both good and bad connotations. It can in positive contexts mean an advanced practitioner or teacher of a martial art. It has also developed some negative connotations, such as a "black belt factory", where a martial arts school may focus on the practice of awarding belts for money without any focus on quality control or imparting skill to the practitioners themselves.