Edited sentence: Indeed many an experienced Judoka feels most comfortable with their back on the ground due to the vast amount of counters and escapes from this position.Judo being one of the few martial arts to teach ground fighting, unlike Karate.Judo's worth regarding self defence comes into its own when it is understood 9 out of 10 street/urban fights end up on the ground.The reason belt colours tend to get progressively darker across all martial arts was so the ancient and poor martial arts participants could keep the same belt throughout their training, dying their own belt to the darker colour as required.Today it is Judo etiquette to place ones surplus belts into a Club pool, so Judoka can exchange belts etc