Like many martial arts, judo uses a belt ranking system that determines the skill level of the judoka.
Since Jigoro Kano invented it in 1882, judo has dramatically evolved, and at some point, it needed a ranking system.
The first ranking system in judo was created by the founder himself, Kano.
The system has undergone modifications since it was invented in 1883, with Kano’s last modifications being in 1931.
It was further developed 7 years later and is still in use today.