Accumulating knowledge from the old jujutsu schools of the samurai, Kano Jigoro formulated his own techniques and, in 1882, founded kodokan judo. Transferring the emphasis from martial to spiritual, Master Kano perceived this system of unarmed combat as a path towards the development of good moral character, leading to greater harmony. Together with the physical training, judo (the gentle way) was seen as a guide to enhancing all aspects of life and this is captured in the saying "maximum efficiency with minimum effort for the mutual welfare and benefit of all". At the outset, judo was recognised as a serious commitment and all those training with Kano Jigoro declared the five oaths below after having signed up to their teaching in blood.

The five oaths of judo
• Once admitted to the kodokan, I shall not stop my study of judo without good reason
• I shall not dishonour the dojo
• I shall not tell or show the secrets I have been taught to anyone, without authorisation
• I shall not teach judo without authorisation
• First as a pupil, later as a teacher, I shall always obey the rules of the dojo

The three main aims of the kodokan were physical education, contest proficiency and mental training which, without the lethal blows, kicks and joint locks, could be taught safely as a competitive sport. Throughout the 20th century, the structure of kodokan judo changed with certain techniques being discarded and new ones being introduced, today many different styles of judo are practiced.

Many complex rules exist in sporting judo but the objective is to throw the opponent cleanly, using the minimum amount of force, or pin him down and immobilise him. A costume comprising loose jacket and trousers, made from strong white cloth, is usually worn. Coloured belts are tied around the jacket, each colour denoting the standard or grade reached by the student.

Today, there are more than six million people practicing judo in over 30 countries throughout the world.