India have won more Olympic gold medals than any other nation — and the fact that the last of them came in 1980 shows the extent to which they dominated the men's event in their early years at the Games.
After Great Britain won the first two hockey competitions in 1908 and 1920 India took over, winning the first of six successive gold medals in their debut appearance at the Games in 1928. Their first defeat in Olympic hockey came in the final in 1960 against arch-rivals Pakistan, who have since added two more titles.
Great Britain's men only made it to the 1984 Games as a late replacement following the boycott by the Soviet bloc, but they went on to win a bronze medal and improved to take gold four years later. The 1988 tournament was also significant because it was the first time that both India and Pakistan failed to win a medal.
Zimbabwe won the first women's hockey gold on their first appearance at the Games in 1980, but the boycott of the Moscow Olympics meant there was no opposition from the Netherlands, West Germany or the United States. Those nations returned to win gold, silver and bronze respectively in 1984, but it was a rare achievement by the Americans to go with their solitary men's hockey bronze from 1932.
Matches are 11 a side with five substitutes. Teams play 35 minutes each way. The pitch, which in London will be synthetic, measures 91.4 metres by 55 metres and the goal stands 3.66 metres wide and 2.14 metres high.
The men's and women's tournaments will comprise 12 teams split into two pools of six. After a round-robin format, the top two in each pool progress to the knock-out stage.
Drawn matches are permitted in the group stages but where a match enters extra time later in the tournament it will be decided by a golden goal. Match umpires operate a three-card system to maintain discipline — green for a warning, yellow for suspension from the game and red for expulsion.