It originated from the many different schools of jujutsu, specifically Tenjin Shinyo-ryu and Kito-ryu, and specializes in throws. Practitioners of judo are called judoka.
Judo teaches the use of leverage, quick movements, and breaking balance (崩し, kuzushi) in order to throw an opponent. Another point is using one's physical and mental power efficiently.
Judo techniques are divided into throws (投げ技, nage-waza), grappling techniques (固技, katame-waza), and striking techniques (当て身技, atemi-waza). Also crucial is learning to fall safely (受身, ukemi).
Nage-waza are divided into standing techniques (立ち技, tachi-waza), and sacrifice techniques (捨身技, sutemi-waza). Tachi-waza are divided into hand techniques (手技, te-waza), hip techniques (腰技, koshi-waza), and leg techniques (足技, ashi-waza). Sutemi-waza are divided into supine sacrifice techniques (真捨身技, ma-sutemi-waza) and side sacrifice techniques (橫捨身技, yoko-sutemi-waza).
Katame-waza are divided into pinning techiques (押込技, Osae-komi-waza), choking techniques (絞技, Shime-waza), and joint locks (関節技, kansetsu-waza)
Atemi-waza include punches, kicks, knee strikes, finger strikes, and elbow strikes. Atemi-waza are only practiced in kata, not free practice, since they could result in serious injury, unconsciousness, or death.
Forms of practice
Judo is practiced in either free practice (乱取り, randori), or kata (prearranged forms).
In randori, any throw can be performed (except a few dangerous throws), and grappling techniques are also performed, except shime-waza. Also exempt from randori include atemi-waza, for the reasons described above.
Katas consist of Randori-no-kata (free exercise katas), which is divided into Nage-no-kata (Throwing kata), and Katame-no-kata (Grappling kata), Kime-no-kata (Decisive kata), Kodokan Goshin Jutsu (Kodokan self- defense kata), Ju-no-kata (Gentle kata), Itsutsu-no-kata (The Five Katas), and Koshiki-no-kata (Kata of Antiquity). There is also Seiryoku-zenyo-kokumin-taiiku (Maximum-Efficiency National Physical Education), which is used by judoka to train outside the dojo.
Sometimes, a judoka is choked into unconsciousness during randori or competition, and resuscitation techniques (活法, kappo) are used to resume their breathing. Kappo are not unlike CPR, but do not involve mouth-to-mouth techniques.
The Kodokan, founded in 1882 by Jigoro Kano, is located in Tokyo, Japan. This is the international judo center. The Kodokan publishes a monthly magazine titled Judo, that Kodokan members subscribe to. Members pay a monthly fee, and international students can enroll.