Olympic judo rules and slang: how to follow Gemma Gibbons in the final

Great Britain's Gemma Gibbons is fighting for gold in the 78kg women's judo final at 4pm BST after her dramatic semi-final victory over Audrey Tcheumeo. Introducing the key rules and terms you need to follow her fight as she takes on America's Kayla Harrison. The basics Contests are fought on a mat, or tatami, 14m x 14m, with a smaller contest area of 10m x 10m inside. The competitors (judokas) win points for throws and holds in a contest lasting up to five minutes. The referee starts the contest by shouting Hajime , and ends it by shouting Matte . Women's judo was introduced to the Olympics in 1992 . The scoring The top move is an ippon ("one full point") which means instant victory. An ippon can be achieved by throwing an opponent on to her back, trapping her in an armhold or stranglehold and forcing her to submit, or immobilising her on the floor for 25 seconds. Other scores are waza-ari ("one half point") – two in the same match mean an ippon, and game over – and yuko , the smallest score that can be awarded. If scores are level at the end, the winner is decided by Golden Score – as it was in Gibbons's semi-final. Like the golden goal in football, this is a dramatic sudden death situation where the first score wins. If there is no score during the period, then the winner is decided by the majority decision of the referee and two corner judges. Rule breaking The referee will intervene if a competitor voluntarily leaves the tatami, uses excessive defence or fails to attack. Warnings include shido for minor infringements, and hansokumake : instant disqualification. Plus: see our interactive guide .