Canadian football is a form of football in which two teams of twelve players each compete for territorial control of a field of play 110 yards long and 65 yards wide, with end zones 20 yards deep. Teams advance across the field through the execution of short, distinct plays, which involve the possession of an prolate spheroid ball (a direct descendant of a size 3 rugby ball). Players advance the ball by carrying it in the arms or passing it to another player (only one forward pass permitted per football play). Three attempts, or downs, are allowed to move forward ten yards, or the team with the ball must relinquish it to the other team.
Canadian football is played at several levels in Canada. The professional league in which the sport is played is the nine-team Canadian Football League (CFL). The professional champion is awarded the Grey Cup, the university champion the Vanier Cup.
Canadian football was originally called rugby football, and is a descendant of rugby union football as played in the 1870s at McGill University. The Canadian Football League was known under various names throughout its history including the Canadian Rugby Football Union, and the Canadian Rugby Union. The Canadian Rugby Football Union, original forerunner to the current Canadian Football League was established in 1884.
The rules of the sport are very similar to American football, and the NFL has established a formal relationship with the CFL. Canadian football retains certain rugby rules which American football has dropped, including allowing a kicker to recover his own kick and advance with the ball. On the other hand, it has eliminated other rules retained in American football, such as the fair catch. One distinctive innovation of the Canadian game is awarding a single point (sometimes called a rouge) for kicking the ball into the goal area and then preventing the opponents from running or kicking it back into the field of play.
Canadian football allows each team only one thirty-second time-out in each half. However, during the last three minutes of each half the clock is stopped after every play, so that additional time-outs would be of little value.
The offensive team must run a play every 20 seconds, while in American football a 45-second interval between plays is allowed.
With the larger field, greater number of players, deeper end zones, more frequent plays, clock stoppages after every play in the last three minutes of the game, returns of every punt and kick, and three downs instead of four, the Canadian game often features more wide-open play than seen in the American game. Specifically, these differences diminish the value of the conservative "three-yards-and-a-cloud-of-dust" tactic that American teams sometimes employ and encourage forward passing and scoring.