Judo: "The way of gentleness".

The word "judo" shares the same root ideogram as "jujutsu": "j?" (?), which may mean "gentleness", "softness", "suppleness", and even "easy", depending on its context. Such attempts to translate ju are deceptive, however. The use of ju in each of these words is an explicit reference to the martial arts principle of the "soft method" ((??, j?h?). The soft method is characterized by the indirect application of force to defeat an opponent. More specifically, it is the principle of using one's opponent's strength against him and adapting well to changing circumstances. For example, if the attacker was to push against his opponent he would find his opponent stepping to the side and allowing his momentum (often with the aid of a foot to trip him up) to throw him forwards (the inverse being true for pulling). Kano saw jujutsu as a disconnected bag of tricks, and sought to unify it according to a principle, which he found in the notion of "maximum efficiency". Jujutsu techniques that relied solely on superior strength were discarded or adapted in favour of those that involved redirecting the opponent's force, off-balancing the opponent, or making use of superior leverage.

The second characters of judo and jujutsu differ. Where jujutsu (??, j?jutsu) means the "art", "science", or "techniques" of softness, judo (??, j?d?) means the "way" of softness. The use of "do" (?), meaning way, road or path (and is the same character as the Chinese word "tao"), has philosophical overtones. This is the same distinction as is made between Budo and Bujutsu. Use of this word is a deliberate departure from ancient martial arts, whose sole purpose was for killing. Kano saw judo as a means for governing and improving oneself physically, mentally, emotionally and morally. He even extended the physical principle of maximum efficiency into daily life, evolving it into "mutual prosperity". In this respect, judo is seen as a holistic approach to life extending well beyond the confines of the dojo.

The Olympic Sport of Judo

Although a fully featured martial art, judo has also developed as a sport.

The first time judo was seen in the Olympics was at the 1932 Games in Los Angeles, where Kano and about 200 judo students gave a demonstration. Judo became an Olympic sport for men in the 1964 Games in Tokyo. With the persistence of Rena Kanokogi, an American, and many others, judo became an Olympic sport for women as well in 1988. It is often stated that the men's judo event in 1964 was a demonstration event, but according to the International Judo Federation (IJF) and International Olympic Committee, judo was in fact an official sport in the 1964 games. Dutchman Anton Geesink won the first Olympic gold medal in the open division of judo by defeating Akio Kaminaga of Japan. Judo then lost the image of being "Japanese only" and went on to become one of the most widely practised sports in the world. The women's event was a demonstration event in 1988, and became an official medal event 4 years later. Men and women compete separately, although they often train together. Paralympic judo has been a Paralympic sport (for the visually impaired) since 1988; it is also one of the sports at the Special Olympics.

Collegiate competition in the United States, especially between UC Berkeley and San Jose State University, contributed towards refining judo into the sport seen at the Olympic Games and World Championships. In the 1940s Henry Stone and Yosh Uchida, the head coaches at Cal and SJSU, developed a weight class system for use in the frequent competitions between the schools. In 1953, Stone and Uchida successfully petitioned the Amateur Athletic Union to accept judo as a sport, with their weight class system as an official component. In 1961, Uchida represented the United States at the IJF meetings in Paris, where the IJF adopted weight classes for all future championships. The IJF was created largely based on the earlier European Judo Union, where weight classes had also been used for many years.

As self-defence

Judo has formed the basis for many military combative and defensive tactics training around the world.

In addition to the above, judo's background in traditional Jujitsu combined with its police and military applications, has resulted in kata specifically designed to teach technical principles for self-defence: Kime No Kata (Forms of Decision) and Kodokan Goshin Jutsu (Forms of Self-defence). Renkoho Waza feature techniques specially designed for police. Joshi Judo Goshinho feature self-defence techniques for women. Other kata sets feature self-defence applications in more subtle ways.

Various aspects of judo principles and training methods promote attributes and skills helpful in self-defence:

• Training with full power and speed against fully resisting opponents: builds speed, stamina, strength, and tenacity.
• Body and mental conditioning by repeatedly being thrown with significant force.
• Training in safe methods to take falls.
• Ability to accurately and quickly use balance, distance, and timing against skilled opponents in fully resistive sparring. Judo practitioners are experts in controlling their opponent's balance whilst maintaining their own.
• Sports Judo rules emphasize rapid transition to pins or submissions after a take-down, which builds skills in explosive use of chokes and locks in self-defence situations.
• Emphasis in controlling one's opponent during throws allow a practitioner to dictate the angle, direction, and force with which their opponent lands on the ground. The consequences could be gentle or lethal, depending on the judo practitioner's intentions.

In mixed martial arts

Using their knowledge of ne-waza/grappling and tachi-waza/standing-grappling, judo practitioners have also competed in mixed martial arts matches. Former Russian national judo champion Fedor Emelianenko is often ranked as mixed martial arts' number one heavyweight in the world. Karo Parisyan is a judo practitioner who fought successfully in the UFC. Rameau Thierry Sokoudjou, Kazuhiro Nakamura and Olympic gold medallist Hidehiko Yoshida were fighters in the now defunct PRIDE FC. Other Olympic medallists and world champions judoka such as Pawel Nastula and Yoon Dong-Sik also fight in MMA. European judo bronze medallist Ferrid Kheder is another MMA fighter with a successful record, as well as Yoshihiro Akiyama and former Olympic judo competitor Hector Lombard. Former WEC middleweight champion Paulo Filho has credited judo and jiu-jitsu for his success. Fighters Sanae Kikuta and Hayato Sakurai also come from judo backgrounds, and Don Frye, a former UFC champion was a practising judoka, quoted judo as one of his official fighting styles. Shinya Aoki, one of the top three light weight mixed martial arts practitioners in the world today also has his background in judo.