Prior to Jigoro Kano establishing the Kodokan in 1882, there were no belt ranks awarded. Practitioners of the martial arts were given scrolls or certificates from their schools to indicate proficiency.
The modern rank system found its roots when Jigoro Kano awarded the rank of shodan (first degree) to Shiro Saigo and Tsunejiro Tomita in 1883. However, at that time there was still no belt awarded. It was not until 1886 that Kano decided that his yudansha (black belt rank) students wear a different color belt than those with lesser proficiency.
Kano was a professor and an educator. One of the differentiators of judo over other martial arts at the time was the establishment of a clear syllabus for teaching and recognizing proficiency at different levels. The award of a black belt officially recognizes the practitioner as a serious student who is capable of pursuing judo at a much more serious level.
As judo grew, Kano thought it appropriate to award different color belts to higher levels of proficiency. In 1930, the Kodokan awarded the red and white belt to sixth-, seventh-, and eighth-degree black belts. Red and white are traditional colors of Japan with white representing purity of the way and red representing the fire of the inner fighting spirit. It is noteworthy that the white color surrounds the red color in the Kodokan symbol. In 1943, the Kodokan authorized the wearing of a pure red belt for ninth- and tenth-degree black belt holders.
While all judo promotions are to be cherished, there are a few that have special recognition. The shodan first degree black belt recognizes the spirit and technical proficiency of a student to begin a serious study of judo.
The rank of yodan (fourth degree black belt) is traditionally considered when a judo practitioner is found to be technically proficient enough to become a teacher of judo and be called sensei.
The rank of rokudan is recognized by the awarding of a red and white paneled belt. While the belt is not always worn while practicing judo, it is worn on special occasions. Generally, the practitioners competitive career included success at the national and international level. Those practitioners who have achieved rokudan have displayed substantial technical ability in teaching students, refereeing, kata and randori, yudanshakai (judo organization) leadership, and moral character. Moral character is important as Kano has indicated that such values as perseverance, respect, loyalty, and discipline are foundational to judo. Generally, those who have achieved the level of rokudan have produced numerous technically and morally competent yodan level sensei from their dojo. They are also recognized as high level judo leaders at the national level.
The rank of kudan authorizes the practitioner to wear a red belt. Very few people received this level of recognition. Generally, the rank of kudan is achieved through continual lifelong practice. Most often, the recipient had a competitive career that included excellence at worldlevel events such as the World Championship and the Olympics. Mastery of all techniques and kata is evident. The recipient has produced numerous students at the rank of rokudan that have continued to build judo around the country and around the world. They have produced numerous national and international champions. They are recognized as high level judo leaders at the international level.
One last overall measurement criterion is time in grade. It is a valuable tool in identifying when people may be tested for proficiency. It answers the question as to whether a practitioner has had time to develop since their last promotion. However, just because a practitioner has had the time to develop, does not always indicate that they have done so to a sufficient level. The national promotion board receives numerous promotion requests from those applicants who have not demonstrated ever increasing levels of proficiency as practitioners, teachers, or leaders. These applications are usually not approved.