Judo, meaning "gentle way", is a modern Japanese martial art and combat sport, that originated in Japan in the late nineteenth century is practiced today by more than 100 million people in more than 200 countries worldwide. Its most prominent feature is its competitive element, where the object is to either throw one's opponent to the ground, immobilize or otherwise subdue one's opponent with a grappling maneuver, or force an opponent to submit by joint locking the elbow or by applying a choke.

Ultimately, the philosophy and subsequent pedagogy developed for judo became the model for almost all modern Japanese martial arts that developed from "traditional" schools.

Techniques & practice
While judo includes a variety of rolls, falls, throws, hold downs, chokes, joint-locks, the primary focus is on throwing and groundwork. Throws are divided in two groups of techniques, standing techniques and sacrifice techniques. Standing techniques are further divided into hand techniques, hip techniques, and foot and leg techniques. Sacrifice techniques are divided into those in which the thrower falls directly backwards and those in which he falls onto his side.

The ground fighting techniques are divided into attacks against the joints or joint locks, strangleholds or chokeholds, and holding or pinning techniques.

A kind of sparring is practiced in judo, known as randori, meaning "free practice". In randori, two adversaries may attack each other with any judo throw or grappling technique. For reasons of safety, chokeholds, joint locking, and the sacrifice techniques are subject to age or rank restrictions. For example, in the United States one must be 13 or older to use chokeholds, and 16 or older to use armlocks.

In randori and tournament practice, when an opponent successfully executes a chokehold or joint lock, one submits, or "taps out", by tapping the mat or one's opponent at least twice in a manner that clearly indicates the submission. When this occurs the match is over, the tapping player has lost, and the chokehold or joint lock ceases.

Combat phases
In judo, there are two main phases of combat: the standing (tachi-waza) and the ground (ne-waza) phase. Each phase requires its own (mostly separate) techniques, strategies, randori, conditioning and so on. Judoka may become quite skilled in one phase and be rather weak in the other, depending on where their interests most lie, although most are balanced between the two.

Judo's balance between both the standing and ground phases of combat gives judoka the ability to take down opponents who are standing up and then pin and submit them on the ground. This balanced theory of combat has made judo a popular choice of martial art or combat sport.

Competition scoring
The object in a judo match is to either throw the opponent to the ground on his back; to pin him to the ground principally on his back; or to force him to submit to a choke, strangle or an armlock. Any of these score, immediately winning the match.

Judo has four grades of score: ippon, waza-ari, yuko, and koka. An ippon literally means "one point" and wins the match.

An ippon is awarded for: a) A throw that lands the opponent largely on their back in a controlled manner with speed and force; b) For a mat hold of sufficient duration (twenty five seconds); c) For opponent submission.
A waza-ari is awarded for: a) A throw that does not quite have enough power or control to be considered ippon; b) For a hold of twenty seconds.

A waza-ari is a half-point, and, if two are scored, they constitute the full point needed for a win.

Yuko and koka are lower grades of score, and only count as tie-breakers - they are not cumulative with one another. Scoring is lexicographic; a waza-ari beats any number of yuko, but a waza-ari and a yuko beat a waza-ari with no yuko. It is not uncommon for a match to be decided based on koka.

A fifteen-second hold down scores yuko and a ten-second hold down scores koka. If the person who secured the hold down already has a waza-ari, they only need to hold the hold down for twenty seconds to score ippon by way of two waza-ari (waza-ari-awasete-ippon). Throws further lacking the requirements of an ippon or a waza-ari might score a yuko or a koka. So-called "skillful takedowns" are also permitted (e.g. the flying arm-bar) but do not score.

If the scores are identical at the end of the match, the contest is resolved by the Golden Score rule. Golden Score is a sudden death situation where the clock is reset to match-time, and the first contestant to achieve any score wins. If there is no score during this period, then the winner is decided by Hantei, the majority opinion of the referee and the two corner judges.

Representation of scores
Judo scoreboards show the number of waza-ari, yuko and koka scores scored by each player. Often an ippon is not represented on the scoreboard, because upon award of an ippon the match is immediately terminated. Some computerized scoreboards will briefly indicate that an ippon has been scored.

Scoreboards normally also show the number of penalties imposed on each player, and sometimes the number of medical visits for each. (Only two "medical" attentions are allowed for each competitor during a match — most often for minor bleeds.)

Electronic scoreboards also usually include timers for measuring both competition time and osaekomi time. A match with the first player scoring one waza-ari, two yukos, and two kokas, beating his opponent who scored one fewer kokas would be displayed on the scoreboard as:

IPPONS