The white belt is the first belt of any martial art. Although the philosophy behind why the belt is white differs from system to system, the first belt is always colorless. White symbolizes cleanliness, or purity. There is no knowledge of Tae Kwon Do at the begginer level. According to my philosophy of colored belts ( which is definitely not correct or incorrect ) dirt and sweat covers the belt from working out. The longer the belt is worn, the darker the belt becomes. That would explain why the first belt is white, or "clean". As the belts progress, or age, they slowly become darker.
The first form that a practitioner is required to learn for testing is Chon Ji. Chon Ji is translated as "Heaven and Earth". Chon Ji contains only 19 movements. In those 19 movements only 2 stances and 3 techniques are used: Down block in a front stance, punch in a front stance, and side block in a back stance. This is a very basic and simple form which offers the student time to focus on basics so the mind does not become distracted by confusing positions. The forms do become more difficult as the ranks progress, but before the student has to worry about more difficult techniques their basics should be improved.
The white belt testing also requires a student to preform a series of one steps. One steps are done with two students whom alternate the position of attacker and defender. One student steps forward and punches at the other student. The defender, or student being punched at, preforms a one step. One steps include evading, blocking, and countering. One steps improve the students ability to judge distance and timing.