The development of belt ranking
The founder of Judo, Jigoro Kano, developed the present ranking system used by most martial arts systems. He expressed rank as a number (7th kyu, 6th kyu, etc.) and assigned belt colors so as to give the student motivation to advance further. Kendo, Aikido, Karate and other martial arts systems have followed this idea.
In this ranking system, novices start at white belt and achieve various colored belts. The black belt is eventually awarded to those who mastered the basics. A colored belt system gives the teacher the ability to see on-sight what level of proficiency the student is and what level of correctness to be given.
In the martial arts there are several hundred different styles. The most widely known karate styles are Shotokan, Shito-ryu, Goju-ryu and Wado-ryu. Hundreds of styles have been developed from these basic styles. Even Shotokan has many different style groups.
Belt rank is not the same from school to school, even in the same style. A student from one university when he transfers to another cannot transfer all their credits to the new school. The same happens for a student transferring from one karate school to another or from one style to another. A colored belt in one school or style does not equal one from another. Each school and style has their own requirements and testing for each rank even if the two styles are using the same belt color system.
Unfortunately, many people persist that one belt rank equals a similar belt rank from another school or style. Sometimes when a student comes from another school, they try to prove their ability in the new school. They then become a source of accidents or they become frustrated because they can't advance as quickly as they did at their last school. They forget that they are there to learn, not to prove their ability.
Sometimes at a traditional school, a student that has been away for a while will be seen wearing a white belt by their own choice even though they may have already earned a higher belt. This indicates humility and a willingness to study from the beginning. This kind of student is usually very promising because they are ready to observe and study new things. They are not obsessed with just earning or showing off their rank but learning about the martial arts. Ego sometimes makes it hard for a person to see things as they really are and to improve oneself. Students need to understand that rank alone is not the goal of Karate but the building of character and learning the essence of the art so that it may be passed on. Remember, what you know and how you perform shows your true rank and skill level, not the color of your belt.