Judo is a Japanese martial art and Olympic sport built on a simple idea: use your opponent's force against them. There is no punching or kicking. Instead, judokas throw, pin and submit each other using leverage, balance and timing. It is a sport where a smaller athlete can beat a bigger one with the right technique, and where a single perfect throw ends the contest instantly.

How a match works

Two judokas fight on a square mat called a tatami, wearing a heavy cotton uniform called a judogi, tied with a belt that shows their rank. A senior match lasts four minutes. If the scores are level at the end, the contest goes to golden score, a sudden-death period in which the first score or penalty decides the winner.

The contest starts standing, with both athletes gripping each other's judogi. The referee calls "hajime" to begin and "matte" to stop the action. Strikes, kicks and punches are prohibited. The fight moves between standing exchanges and groundwork, and the referee can stand the athletes back up if the groundwork stalls.

Judokas are grouped into weight classes so that size is not the deciding factor, with separate divisions for men and women. The sport is governed worldwide by the International Judo Federation, the IJF.

Scoring: ippon and waza-ari

Judo scoring is built around the ippon, the full point. An ippon ends the match immediately and is awarded for a throw that lands the opponent largely on their back with speed, force and control, for holding the opponent down for 20 seconds, or for a submission through a chokehold or joint lock that forces the opponent to tap out.

A waza-ari is a half point, awarded for a throw that is close to ippon standard or for a pin lasting between 10 and 19 seconds. Two waza-ari combine into an ippon, which ends the match. This is the waza-ari awasete ippon rule.

A third score, yuko, used to exist for smaller techniques, but it was removed from elite competition in 2017, leaving a simpler two-score system. Penalties called shido are given for passivity, illegal grips, stepping out of the area or avoiding engagement. Repeated shido penalties can lead to disqualification, so stalling is not a viable tactic.

Throws and groundwork

Judo techniques fall into two main groups. Nage-waza, the throwing techniques, includes standing throws such as o-soto-gari, the major outer reap, and uchi-mata, the inner thigh throw, as well as sacrifice throws in which the attacker falls with the opponent. A good throw needs kuzushi, breaking the opponent's balance, before the technique itself.

Katame-waza, the grappling techniques, covers what happens on the ground. Osaekomi-waza are the pins that hold the opponent on their back. Shime-waza are chokeholds that restrict blood flow. Kansetsu-waza are joint locks, limited to the elbow in competition. Before any of this, beginners spend their first sessions learning ukemi, the breakfalls that let them land safely when thrown.

Belts and ranks

Judo uses a belt system to show a practitioner's level. Beginners start with a white belt and progress through the kyu grades, typically yellow, orange, green, blue and brown, before reaching black belt. Black belt is not the end: it is the first dan grade, and there are ten dan ranks in total, with higher dans recognising decades of skill and contribution to the sport.

The exact colours and order can vary between countries and organisations, but the principle is the same everywhere: the belt marks the journey, and a black belt is the beginning of serious study, not the end of it.

Formats and major competitions

The biggest events in judo are the Olympic Games, where judo has been contested since Tokyo 1964, and the World Championships, held annually except in Olympic years. The IJF World Tour runs through the season, with Grand Slam and Grand Prix events in cities around the world where athletes earn ranking points and Olympic qualification.

Continental championships, such as the European and Asian Championships, and team events, in which nations fight each other in a series of bouts across the weight classes, complete the calendar.

A brief history

Judo was founded in 1882 by Professor Jigoro Kano, who developed it from the older art of jujitsu and opened the first school, the Kodokan, in Tokyo. Kano's principles were maximum efficiency with minimum effort and mutual welfare and benefit, ideas that still shape how the sport is taught.

The International Judo Federation was founded in 1951, and the sport spread from Japan around the world. Weight classes were introduced as the sport grew internationally, and judo joined the Olympic programme in 1964. Today it is practised in almost every country, as a competitive sport, a self-defence system and a way of training discipline and respect.

How to follow it

If you are new to judo, watch for the ippon. A clean throw that sends an opponent flat onto their back is the sport's most dramatic moment, and it ends the contest on the spot. Then watch the grips: the battle for a good grip decides most matches before a throw is even attempted. And remember that a judoka who is behind can win in a single second, because one throw is all it takes.