First down

A down is a period in which a play transpires in American and Canadian football. The down is a distinguishing characteristic of the game compared to other codes of football, but is synonymous with a "tackle" in rugby league. The team in possession of the football has a limited number of downs (four downs in American football, three downs in Canadian football) to advance ten yards or more towards their opponent's goal line. If they fail to advance that far, possession of the ball is turned over to the other team. In most situations, if a team reaches their final down they will punt to their opponent, which forces them to begin their drive from further down the field; if they are in range, they might also attempt to score a field goal.

A down begins with a snap or free kick (such as a kickoff or safety kick), and ends when the ball or the player in possession of it is declared down by an official, a team scores, or the ball or player in possession of it leaves the field of play.

The player with possession of the ball after he has been tackled or is otherwise unable to advance the ball further on account of the play having ended (e.g., "He is down at the 34 yard line") is down.

Down may also refer to the ball after it is made dead in one manner or another. The line of scrimmage for the next play will be determined by the position of the ball when it is down.

Each possession begins with first down. The line to gain is marked 10 yards downfield from the start of this possession, and the situation is described as "1st and 10" (if the goal line is less than 10 yards downfield, then the goal line is the line to gain and the situation is "1st and goal"). If the offensive team moves the ball past the line to gain, they make a new first down. If they fail to do this after a specified number of downs (four in American play and three in Canadian play), the team is said to turn the ball over on downs, and possession of the ball reverts to the opposing team at the spot where the ball was downed at the end of the last down.

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