Competition details
In the men's competition, 16 teams qualify and are divided into four groups.
Within the groups, the countries each play one another - with points awarded for
a win and draw. The top two teams in each group advance to quarter-finals.
In the quarter-finals, extra-time will be played - but the first goal
determines the result and the end of the match. If no goal is scored in
extra-time then penalties decide the result.
The women's game is similar. But there are only two groups of five, and the
top two teams in each will go forward to the semi-finals.
Five facts
1) Football was one of the first team sports to be introduced to the Olympic
Games. It appeared in 1900 - along with cricket, rugby and polo.
2) Olympic football was weakened by the World Cup which began in 1930 and it
was excluded from the programme in 1932.
3) The 1984 Games in Los Angeles saw professionals allowed to compete at the
Games for the first time.
4) In Atlanta, 1996, women's football became an Olympic sport.
5) Great Britain won gold medals in 1900, 1908 and 1912.