You've probably heard a little bit about belts in martial arts. A person's belt color shows their progress in the martial art. It's kind of like a rank or skill level. Every two or three months, you attend a belt exam, which determines whether or not you will advance to the next belt color. The test covers all the things you regularly do in class. These include basic kicking, blocking, and striking; physical fitness; forms; and sparring. There is also a board breaking portion. Additionally, you are graded on things like energy, self-control, and spirit.
Below is a chart of all the belt colors, in order of progression. Your belt level determines what forms and moves you will learn, which get more and more difficult as you advance. As you can see, the belt colors get darker and darker until you reach the last one: black belt. However, even after achieving the rank of black belt, you can continue your training and advance through the degrees of black belt (first, second, third, etc.). Thus, you never really reach the end of your training. There is always more to learn.