Belt history
Until 1882, there was no kyu (kyu is the Japanese equivalent of gup) or dan ranking system. Prior to this, most traditional Japanese arts of the period used the complicated menkyo ranking system to license student skill levels. The ranks were usually shoden, chuden, okuden, mokuroku, menkyo, and menkyo kaiden (license of total transmission) but the order and titles of the license often differed between the different arts.
The ranks were usually awarded using specially created certificates or handwritten letters from the licensing teacher or founder. Often, the higher ranks were also presented with a densho, manuscript scrolls of instructions or records of secrets recorded by the school founder. Some densho provided detailed instructions and graphic illustrations of particular techniques, while others used descriptive words or characters that served as memory aids for advanced techniques. Some of these documents were meaningless to outsiders unfamiliar with the specific language of the particular art.
Due to the secretive nature of the arts and their instructors, there was no way to evaluate or compare equivalent skill levels of students from different schools. The minimum time in rank between the licenses varied between on the schools.
As a youth, Jigero Kano first learned the basics of Jujutsu from Teinosuke Yagi. Later, he studied tenshin shinyo ryu Jujutsu under Hachinosuke Fukuda and Masatomo Iso, as well as kito ryu Jujutsu under Tsunetoshi Iikubo so he was familiar with the secrets of both schools.
After founding Judo 1882, Kano researched other styles of Jujutsu, including examining their densho. From his findings, Kano revised the Judo ranking system, creating ten ranks with relatively short intervals between them to keep students interested in progressing through them. In 1883, Kano further divided students into two groups, the non-graded "mudansha" (kyu ranks) and the graded "yudansha" (dan ranks). Grade certificates were issued starting in 1894.
Black belts were not worn as symbols of Judo dan grade until about 1886. However, these belts were not the same as belts worn today. Since Kano had not yet invented the Judo uniform, Judo students practiced in a "kimono" (the traditional Japanese robe) and wore the wide belt that is still worn with the formal kimono. In 1907, Kano introduced the modern Judo uniform and belt, but he still only used white and black belts.
Gradually, colored belts were used to differentiate the kyu ranks. In Japan, white belts are generally worn through all kyu grades, although some schools also use the brown belt to indicate the higher kyu ranks. The blue, yellow, orange, green, and purple colored belts used by intermediate kyu grades originated in Europe and were imported into the U.S. system during the early 1950s.
Black belts are traditionally worn by the technical ranks, first dan (shodan) through fifth dan (godan). A red-white sectioned belt is worn by the ranks awarded for service to Judo, sixth dan (ryokudan) through eight dan (hachidan. Solid red belts are used for ninth dan (kudan) and tenth dan (judan).
Gichin Funakoshi brought karate to Japan from Okinawa in the 1920's. Until that time, Okinawa karate students did not have special uniforms; they trained in their everyday clothes. Funakoshi adopted the Judo kyu/dan ranking system and a modified Judo uniform to encourage Japanese acceptance of karate. He awarded his first shodan ranks in 1924. Most martial art styles that have ranking/belt color systems adopted them from Japanese karate.
The belt encircles its wearer. The circle is a universal symbol of wholeness and harmony, and symbolizes the totality of the universe. The circularity of the belt reinforces the circular cycle of Taekwondo training; the fact that, after years of training, one realizes that the true essence of Taekwondo existed at the beginning.
As a practical matter, the Taekwondo belt holds the uniform closed, but its real significance is far greater than merely being a clasp or even a signifier of rank. The belt has symbolic meanings, both in eastern philosophy and in its color.
Sources
Cunningham, D. (2004). Belt Colors and Ranking Tradition. [Online]. Available: http://www.e-budokai.com/articles/belts.htm. [2004, July 1].