The first official rules of soccer were drawn-up by the English Football Association in 1863. These rules, known as the Laws of the Game, are now governed by the Fédération Internationale de Football Association, commonly known as FIFA. There are 17 rules currently listed by FIFA; the seventh law deals with the duration of a regulation soccer game.
A regulation soccer game is divided into two halves of 45 minutes each. These two periods combine to make up the standard 90 minute length of a soccer game. The official FIFA Laws of the Game states the standard match length can be altered before the game begins if the referee and both teams agree. Such an occurrence is very rare in professional soccer. The threat of insufficient light is the most likely cause of reduced game time, but the use of floodlights in modern soccer largely negates this problem.
All players receive a break after the first half of the game. The halftime interval cannot last more than 15 minutes and all the players must be out on the field of play after this period. FIFA regulations allow the referee to alter the length of the halftime interval if necessary, but this situation rarely occurs in professional football. Instances of floodlight failure or crowd trouble can sometimes lead to an extended halftime interval, allowing time for any problems to be resolved.
Injury time, also known as stoppage time, is often added to the end of the first and second halves of standard time. A number of situations can lead to the extension of each 45-minute period. The most common reasons include time taken to make substitutions, the treatment of injured players and deliberate acts of time wasting by individual players. The referee decides how much injury time, if any, should be added at the end of either period. The time added rarely exceeds five minutes.
Some competitions, such as knockout tournaments, do not permit a tied final score after 90 minutes of play. In this instance, 30 minutes of extra time are added to give both teams the opportunity to win the contest. Extra time, also known as overtime, consists of two 15-minute halves. The players are allowed a five-minute interval between these two halves.
If extra time does not provide an outright winner, a knockout game is often decided by a penalty shootout. Each team nominates five players to take a penalty kick at goal. If both teams score the same amount of penalties then the shootout goes to sudden death. There is no set duration for a penalty shootout as the game must be resolved with a clearly decided winning team.