Modern judo (formally known as kodokan judo) is the result of a synthesis of a number of medieval Japanese fighting systems made by Dr. Jigoro Kano (1860–1938) in 1882. Modern judo is closest in form to the older martial art of jujitsu. Judo, a Japanese term that translates as "the gentle way," incorporates a complex series of throwing maneuvers, wrestling and grappling techniques, including pin moves, choke holds, and joint locking holds in the course of combat. Judo was first introduced into Olympic competition in 1964, and it has subsequently become accepted as a high level sport for both men and women. Judo has significant world wide appeal both as a recreational club activity, with participants who seek a measure of improved physical fitness and personal pleasure, as well as status as an elite level sport.
Worldwide judo competitions are sanctioned through the International Judo Federation (IJF), an organization with national governing body members in most nations of the world. Judo is organized as a weight category competition, as larger athletes would possess a natural competitive advantage against smaller athletes, given the nature of judo and its physical requirements.
Judo has a standardized ranking system for its participants, which may range from children under 10 years of age to persons in their 70s and beyond. Athletes are judged on their ability to execute various standard throws and holds; the athlete is awarded their judo "belt" with the color of the belt signifying their level of proficiency. Black belts are reserved for the masters of the sports, known as dans—a tenth level black belt is the highest level ever awarded in
Unlike other forms of martial sport, such as boxing or karate, success in judo is not bases on the ability of the competitor, referred to as a judoka to strike more quickly or to strike an opponent harder. Judo is a sport of coordination, where balance, strength, flexibility, and timing are employed create tactical advantages. In the period prior to 1900, judo formalized many of its movements and techniques. A result of this process was the definition of the proper judo throws in the Goyko No Waza, the standard syllabus of all judo. The syllabus is updated through consultation with the international judo community, with the last revision providing for the inclusion of a total of 67 different throws. Many throws involve the competitor using their hands, feet, and body in combination; a certain number of the throws are counter throws, where the defender converts the power of the attacking athlete's movement into the energy in their own response.
All judo participants wear an identical uniform, the judogi. The competitors wear no other clothing or footwear during the course of competition.
The objective of competitive judo is to defeat the opponent in one of three ways—to successfully throw the opponent on to their back; to hold the opponent on their back for a period of 25 seconds; to disable the opponent by way of a choke hold or an armlock that prevent further opponent movement. Judo is the only Olympic sport where choking or the potential fracture of an opponent's arm are legal techniques.
Throughout the course of the contest, the judoka are scored in their movements by three judges, one of whom who is on the mat, the remaining judges are positioned on the edges of the competitive surface. The judges assess not only the raw numerical value of the score, but the quality or any impressive aspect of a single maneuver. Points are also scored through the award through penalty; points are not deducted from the offender's score, but added to the opponent's tally.
As a general rule, a judoka may attempt to knock over the competitor by attacking their legs, by sweeping the feet of the opponent from under them, or by performing one of the many permitted throws. Much of judo success is built upon the ability of a competitor to execute the desired throw while establishing a low center of gravity through which to move dynamically across the mat. Many judo moves are also executed in mid-air, and the understanding by the judoka of the importance of maintaining a low center of gravity is essential in landing in a stable position.
The brute strength that athletes often develop through weight training may assist in judo, but will never likely be determinative as to competitive success. Training exercises that emphasize balance and coordinated movement within which the athlete is able to move explosively are the foundation of judo success. As the body of a judoka may be twisted and contorted by the application of opponent force during an event, stretching to achieve maximum flexibility and range of joint motion are essential to prevent fluid movement and to assist in the prevention of injury.