"There are many explanations of meanings of Belt colors as some martial arts is differs in the belts order and Dan and belt colors varies in each different karate schools"

Belts colors vary by ranks (Dan) evaluate the performance of the player or the trainee and the evolution of his physical and mental skills
But Did you thought the meaning of of each color? The explanation for the choice of this particular color for Level of player?!!

Simple Karate Belts colors

Note: in the past there was no colors but white and then put other colors so that there is becomes a competition between players.
The red color belt may be only in championships and matches in order to distinguish between players of Karate 
The meaning for Colors of belts in karate

White Belt..
The color of innocence..This belt color means white Paper Skip fingertips of Sensi
Yellow Belt..
Color of the sun .. This belt color means new Sunrise days
Orange belt ..
Color of the Awakening..This belt color means that fun of awakening discovery of mind control skills.
Belt green ..
Color of growth.. This belt color means that when a player starts skills growth as Flowers blooming.
Blue Belt ..
The color of the sky .. This belt color means the expansion of prospects for trainee.
Brown belt ..
Color of the earth .. This belt color means that when deepening the roots of the trainee in the ground.
Red belt ..
Color of the danger.. Where should the enemy or waist and a friend to be careful.
Black Belt..
Unlike White.. It is a combination of developments common mental, physical and emotional.

List of Colors of belts in karate and variation with the Student Karate Level and Student Rank or Dan:
10th Kyu White
9th Kyu Yellow Belt
8th Mon Kyu Orange With Green Stripe
8th Kyu Orange With White Stripe
7th Mon Kyu Orange With Red Stripe
7th Kyu Orange Belt
6th Mon Kyu Blue With Green Stripe
6th Kyu Blue With White Stripe
5th Mon Kyu Blue With Red Stripe
5th Kyu Blue Belt
4th Mon Kyu Purple With Green Stripe
4th Kyu Purple With White Stripe
3rd Mon Kyu Purple With Red Stripe
3rd Kyu Purple Belt
2nd Mon Kyu Brown With White Stripe
1st Kyu Brown Belt
Then Black belt earned from the  1st Dan Black belt till 10th Dan Black Belt 10th Dan, thus is the Highest Dan in Karate where the student starts out at a low rank of belt (white) and progresses through the ranks (kyu and dan) to make it to the top (black) to instruct students him/her self.

List the Colors of belts in karate from the Lowest Dan to the Highest Dan
Mukyu White
10th Kyu Yellow Belt
9th Kyu Orange Belt
8th Kyu Blue Belt
7th Kyu Purple Belt
6th Kyu Green With White Stripe
5th Kyu Green Belt
4th Kyu Green With Black Stripe
3rd Kyu Brown With White Stripe
2nd Kyu Brown Belt
1st Kyu Brown With Black Stripe
Then Black Belt colors variations from  1st Dan Black Belt that earned when Karate student Rank is 1st Dan Black until the 9th Dan Black Belt which earned when Karate student Rank is  9th Dan of black belt.
Where the highest the student grade the highest the player Rank in martial arts and a great skill

Even within a particular style, there are many variations between schools. However, there is a general trend in most schools and styles to work up from a white belt to a black belt in gradually darkening colors.

Abstract: 
Colors of belts in karate generally get darker through each Karate level towards Black Belt. This may be symbolic of the time when a plain white sash (Obi) was used to tie a plain white tunic for practice.
If a student trained often enough, the white Obi would eventually darken. This seems a likely reason for the Karate Black Belt to symbolize the most advanced Karate Level.
Colors system of Karate belts and other Martial arts Belts make the student of Karate school need to do Skill building of every Belt Level  to enter the belt Exam in Karate championships.