Motivation for some, representation of a technical level for others, the one we call 'Obi' (帯) in Japanese, also helps more prosaically to keep the judogi closed. Whatever its role or its attribute, it is a fundamental element which distinguishes judo and martial arts from any other sport discipline.
From the very beginnings of judo, from 1882, the question of keeping one's uniform (judogi) closed arose. It had to be done in a suitable way and without presenting danger to a judoka or their partner. Any buttoning was prohibited and so the principle of the belt was quickly adopted. As the belt was born, Professor Jigoro Kano gave it meaning, just as quickly.
Concretely, beyond the need to maintain the judogi, the belt must be robust enough to withstand the grips and pulls that are applied to it. It should also be wide and thick enough not to injure the wearer. It is thus made up of several layers of stitched fabric, lengthwise. The belt allows certain techniques to be executed while standing and although international regulations prohibit the permanent grip on the belt, it can be used for offensive purposes, as well as in ground work.
The different belts that one obtains, during life as a judoka, mark progression in the sport. Studying judo is a long-term process, which ideally begins at a young age, although it is possible to begin judo study as an adult. Obtaining grades is therefore a continuous process that motivates the practitioner to know more. As such, the black belt has a mysterious dimension. Being a black belt in judo means knowing things that other people don't know. However, as the practice progresses, step by step, everyone has the possibility of reaching this philosophical grail and in turn being part of ‘those who know.’ At the beginning the black belt is a dream idealised by the child, but gradually, it becomes the goal that one sets and that one can achieve through work and diligence.
It is therefore important to underline that the ranks are not and cannot be automatic. They guide the evaluation of technical level, the effectiveness in combat and the degree of seniority, as well as moral qualities, which correspond to the scrupulous respect for the moral code alongside a sufficient investment in practice. Without a minimum of respect for the required rules, no judoka can claim to obtain a rank.
Coloured belts, as we know them today (from white to brown), were invented in England in the mid-1920s and then introduced in France by Professor Mikinosuke Kawaishi, where he developed the concept further, under the aegis of the French Judo Federation.
More recently, two-tone belts have been introduced in certain countries (white-yellow, yellow-orange, orange-green or green-blue), representing intermediate grades which allow the progression of the youngest to be spread out, knowing that it is commonly accepted that the first dan black belt can be obtained from the age of 15 or 16 years.
The white to brown coloured belts correspond to grades called kyu, ranging from the highest numbered for the white belt, to the ‘1st kyu’ for the brown belt. These levels are sanctioned by the judo teacher, who takes into account, during a proper exam organised in the club, technical criteria, results or participation in various competitions and events and the behavior of the student (linked to the moral code of judo). The teacher also considers attendance throughout the year and attitude towards other practitioners.
Hereafter, the levels are called dan. We thus find from 1st dan to 5th dan a black belt: Sho-dan (1st), Ni-dan (2nd), San-dan (3rd), Yo-dan (4th), Go-dan (5th).
Then the 6th (Roku-dan), 7th (Shichi-Dan) and 8th (Hachi-dan) dan are represented by a belt with wide, alternating red and white bands, the difference in Europe between grade being sometimes marked, in principle, by the difference in width of the coloured bands (6th dan white-red 20 cm, 7th dan white-red 15 cm, 8th dan white-red 10 cm - This doesn't apply for the Kodokan grades). The 9th (Ku-dan) and 10th (Ju-dan) are symbolised by a red belt.
Some references explain and people belive that: "Being himself 11th dan, Jigoro Kano did not deliver grades beyond 10th. Today, this still represents a limit which cannot be exceeded. Symbolically, after his death he was awarded, by Jiro Nango, his nephew and successor at the head of the Kodokan, the 12th dan, represented by a wide, white belt. Philosophically, this meant that after having learned everything, even invented everything, it was necessary to relearn everything. The awarding of this 12th dan took place in 1940, the year the first Tokyo Olympic Games should have taken place, for which Professor Kano had been the spokesperson for Japan's candidacy. At that time, already the highest ranking judoka, with his 10th dan, this 12th dan created an insurmountable gap that no-one will ever be able to bridge."
But this is actually a legend. “Kano Shihan has no dan grade, because he was the master who allowed his students to hold Dan grades. Nobody could give him Dan grade, because he was the founder of Kodokan Judo.” (source: Kodokan). According to historical literature, Kano Shihan mentioned there are no upper limit of Dan grade. However, 10th Dan is the highest grade ever given in history.
If we go back a little through the history of judo, we quickly discover that the differentiated belts are an invention of Jigoro Kano, even if the exact date of their creation is not entirely clear. Did they exist as soon as Kano awarded the first dan, in 1883, a year after the invention of judo? What seems certain is that as early as 1886, certain illustrations seem to corroborate the existence of a belt system, even if the first written mention dates from 1913.
To create his rank system, Professor Kano was inspired by the 'Menkyo' reward method, dating from the 16th century and corresponding to certificates presented in rolls. On each was written various information, such as the recipient’s name, their level, the techniques learned and the the duration of the training, among other items included.
Even if the colours were limited (white, brown, black), we can therefore say that from the start Jigoro Kano thought about a coherent system to mark the level of his students.
Here is what the inventor of judo said about his grading system, “I founded the Kodokan in the year 15 of Meiji  and established the ranks of the practitioners without delay. In the past, depending on habits, the number of ranks differed and each one was given scrolls with various names, but generally there were three main divisions which were mokuroku, menkyo and kaiden. I felt there was too much time between each one for this to be of any help in terms of motivating practitioners. So, I baptised the beginners mudan-sha [people without dan] which I separated into three divisions, kô, otsu, hei and I set up a system in which we became 1st dan after a certain progression in practice then 2nd, 3rd , 4th dan and so on upwards, causing the 10th dan to be awarded to people who in the old system would have reached the kaiden level. Subsequently, I still felt that with my system of three stages kô, otsu and hei for people without dan, the time was always too important between two to motivate them and I reformed the system by establishing a 1st, a 2nd , a 3rd, a 4th, a 5th kyû as well as a non-grade, which corresponded to six kyû. Thinking about it with the experience gained since then, I think it fits the needs quite well."
From 1913, the kyū are divided into 2 belt colors, the white belt (5th and 4th kyū) and the brown belt (from 3rd to 1st kyū) for adults, while young practitioners wore a purple belt instead of the brown belt. Initially, the dan was divided into two colors: the black belt for 1st to 9th dan and the red belt for 10th. It was not until 1931 that the red and white belt appeared for the grades of 6th to 9th dan inclusive and finally in 1943, the 9th dan judoka were authorised to wear the red belt.
In 1926, Japanese master Gunji Koizumi, founder of the British Judo Association and of the first European dojo and therefore considered the father of British judo, made an invention that revolutionised the rank system. He introduced additional color belts. As early as 1927, these new belts appeared in the Budokwai reports. In Gunji Koizumi's programme there are five colors (white, yellow, green, blue and brown), to which orange was added, to correspond to the six kyū of the Kōdōkan at the time. Without it being possible to be verified, there is a possibility that the colours were based on the color of the billiard balls.
In 1935, another Japanese expert, Mikinosuke Kawaishi, after a stay in England, introduced coloured belts in France and developed a teaching programme associated with it, that would soon be called the “Kawaishi Method.” These inventions and developments corresponded fully with the western way of thinking and allowed judo to flourish, especially among the youngest members of society. This coloured belt model quickly became the benchmark. Two-tone intermediate belts were introduced in France in 1990, allowing a young, assiduous judoka to pass one belt per year from the age of six, in order to be able to prepare for the black belt upon entry into adolescence.
The grade system invented by Jigoro Kano and developed by other experts was so successful that it was taken up by other martial arts and even other sports which adapted a ranking system as well based on the same concept. This kyū/dan system is still the most widely used today.
It is important to remember, however, that the belt is not an end in itself, but that it represents the journey taken through everyday practice. In training, it gives a visual indication so that a partner can adapt their level and vice versa. In competition it is more difficult today to see that distinction, as almost all the athletes of the international circuit are wearing the black belt and the wearing of a red and white belt (minimum grade of 6th dan) is not allowed in competition.
Nevertheless the belt fulfills an important mission of respect and responsibility towards the lower ranks. It is a personal attribute, reflecting a level and the work done. It takes on a philosophical dimension which prohibits the practitioner from using the techniques learned inside, outside the dojo. On the other hand, it implies judoka should consider the values of the moral code of judo as one's own, in everyday life.
The belt and therefore the rank represent the values of mind and body that we also find in the idea of SHIN-GHI-TAI (mind, technique, efficiency) that we teach to young judoka from the first years onward. This is why, when you tie your belt, it is important that the two ends have the same length, because they are a symbolic representation of the mind and the body, which, for a balanced life, have the obligation to exist in harmony. It is also important to tie your belt knot correctly; it must be horizontal! A knot whose two ends protrude vertically, symbolically cuts the physical and spiritual energies which emanate from the stomach (the hara). Let us not forget that judo is a discipline of Japanese origin and that, for the Japanese, our stomach or “hara” is the reservoir of our energy. Centered on it, we show confidence and serenity. Cut off from it, the slightest shock can make us falter.
Finally, it is not impossible that originally the belts were white, for a beginner, but lost their whiteness, becoming black when the judoka practised assiduously, hence the progression from white to brown and then black. The story may appeal to younger people and once again it is loaded with symbols. What is certain is that the judoka's belt means something. It is not just a piece of fabric that is tied around the waist. It implies rights and duties and it binds is all to the values that must be passed to future generations.