Judokas are disallowed from kicking, clawing, using arms or hands against the face, or stepping outside the shiago. The object is to throw each other via hip throws, foot/leg techniques, arm locks, strangles, or "sacrifice" maneuvers in which vulnerability is displayed but opponent aggressiveness is converted into imbalance.

The scoring system is progressive: a koka (3 points) is a throw in which an opponent is knocked to their hips and held for between 10 and 20 seconds. More valuable is a yuko (5 points), which lasts 20-25 seconds. A waza-ari (7 points) is a throw that immobilizes an opponent for 25-30 seconds, and two of these equals an ippon (10 points). An ippon ends a match immediately, and any hold that ends with submission is an instant ippon.

Matches last five minutes, and any match that goes the distance and not by ippon is settled by score. There are seven weight classes each for men and women, and all are contested, single-elimination bracket-style, in one day. Here's Mark Huizinga, 2000 half-middleweight Olympic champion from the Netherlands, ipponing his way through the field on the way to gold.

Judo Fun Facts:

• The sharply dressed referee can usually be heard barking commands to the judokas. Some of these are: "Yoshi!" (Keep fighting!), "Matte!" (Wait! Stop the match!), and "Sono mama!" (Freeze! Do not move!)

• Each weight class is divided into two pools, and each winnows itself down in the course of one quick day. But there's a twist. Losers must wait until the completion of the pool, hoping their conqueror wins. If he or she does, the judoka is entered in a repechage pool, the winner of each wins a bronze medal.

• Each weight class awards two bronzes. The two repechage pool winners have done enough fighting for a day.

• At Barcelona 1992, two judokas from Israel gave their nation its first medals since Black September terrorists claimed the lives of 11 members of the Israeli delegation two decades earlier. Yael Arad won a silver in the women's half-middleweight event, and Oren Smadja won bronze in the men's lightweight class.

• Part of giving a domestic sport to the world for Olympic purposes means that other countries might get good at it -- that can bruise the pride a bit. Huizinga was part of a wave of judokas who won gold in the traditionally Japanese-dominated sport at Sydney 2000; only four of the 14 weight classes were won by the Land of the Rising Sun. Japan regrouped and won eight gold medals in Athens.

In 2008:

The 14 judo tournaments will be held between August 9 and 15 (Days 1-7) at the Beijing Science and Technology University Gymnasium. A total of 386 judokas will take part.

There will once again be seven weight classes, and each country can enter one athlete in each. For men: extra-lightweight (up to 132 lbs.), half-lightweight (145 lbs.), lightweight (164 lbs.), half-middleweight (172 lbs.), middleweight (198 lbs.), half-heavyweight (220 lbs.) and heavyweight (over 220 lbs.). On the women's side: extra-lightweight (up to 106 lbs.), half-lightweight (114 lbs.), lightweight (125 lbs.), half-middleweight (138 lbs.), middleweight (154 lbs.), half-heavyweight (172 lbs.) and heavyweight (over 172 lbs.).

All-Time Medal Standings:

Nation	Gold	Silver	Bronze	Total
Japan	31	14	13	58
France	10	6	17	33
South Korea	8	12	13	33
Cuba	5	8	13	26
Soviet Union	5	5	13	23
China	5	2	7	14
Netherlands	4	1	10	15
Poland	3	4	2	9
Spain	3	1	2	6
Brazil	2	3	7	12
Italy	2	2	6	10
Germany	2	1	11	14
Belgium	2	1	7	10
Austria	2	1	1	4
Unified Team	2	0	2	4
West Germany	1	4	3	8
East Germany	1	2	6	9
Hungary	1	2	4	7
Georgia	1	1	2	4
North Korea	1	1	2	4
Switzerland	1	1	1	3
Belarus	1	0	1	2
Turkey	1	0	1	2
Greece	1	0	0	1
Great Britain	0	6	9	15
United States	0	3	6	9
Russia	0	3	5	8
Canada	0	2	2	4
Mongolia	0	1	3	4
Australia	0	1	2	3
Bulgaria	0	1	2	3
Israel	0	1	2	3
Ukraine	0	1	1	2
Egypt	0	1	0	1
Slovakia	0	1	0	1
Uzbekistan	0	1	0	1
Estonia	0	0	3	3
Romania	0	0	3	3
Yugoslavia	0	0	2	2
Czechoslovakia	0	0	1	1
Iceland	0	0	1	1
Kyrgyzstan	0	0	1	1
Latvia	0	0	1	1
Portugal	0	0	1	1
Slovenia	0	0	1	1

(Photo via 2004 Official Report)