
Around the 1920's. the KYU/Dan system was adopted into Shotokan.
This system used colored belts as an indication of rank. Originally, Karate had only 3 obi (belt) colours, white, brown and black, with several ranks within each. Here is the original belt system, still used by Shotokan Karate of America.
Most schools use the kyu/dan system but have added other colours. The most common, used by the most large mainstream, international Shotokan associations (including Shotokan 2000) is given below but other variations exist.