A down is a period in which a play transpires in gridiron 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 instead 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 is down (e.g., "He is down at the 34 yard line").
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.
If a penalty against the defensive team moves the ball past the line to gain, the offensive team gets a new first down. Some defensive penalties give the offense an automatic first down regardless of the distance.
When the offensive team has not yet made a first down before reaching the final down, the team faces a last down situation (third down situation in Canadian play and fourth down situation in American play), where the team is forced to decide whether to either scrimmage the ball in an attempt to pick up the first down (this is called going for it [on fourth down]), or alternatively to kick the ball (either by punting or making a field goal attempt). Though statistical analysis of games suggests playing more aggressively is the better option, kicking the ball is typically seen as the safer solution; scrimmaging may lead to a turnover on downs, potentially giving the ball over to the other team with good field position.
Downing the player with possession of the ball is one way to end a play (other ways include the player with the ball going out of bounds, an incomplete pass, or a score). Usually a player is made down when he is tackled by the defense. In the NFL, if the offensive player is touching the ground with some part of his body other than his hands or feet, then he is down if any defensive player touches him. In the NCAA, an offensive player touching the ground in the same manner is down, regardless of whether a defensive player touches him.
If recovering the ball in one's opponent's end zone (following a kick-off in American football, and following any kick into the end zone, except for successful field goals, in Canadian football), a player may down the ball by dropping to one knee (note that in Canadian play, doing so scores a single for the opposing team). A player in possession of the ball will down the ball if he fumbles it out of bounds. If a quarterback is running with the ball during his initial possession of the same play following the snap, he may down the ball by voluntarily sliding from his feet to a sitting or recumbent position - this is to protect the quarterback from injury. In the NFL, the quarterback is the only player for whom falling down in this way automatically stops play.
The situation at a down can be described succinctly in a short phrase of the form 1st/2nd/3rd/4th & X. The first part describes which down of the set of four the offense is on, and the X is a number of yards between the current line of scrimmage and the line at which the offense would gain another set of downs. Thus, offenses will normally begin on 1st & 10. If they were to gain 5 yards on the play, the subsequent situation would be described as 2nd & 5.
If the distance to the target line is very small, the number of yards may be replaced by & inches (i.e. 3rd & inches). Colloquially, when the target line is far from the line of scrimmage, the term "& long" may be used (i.e. 3rd & long).
When an offence has a first down within 10 yards of the goal line, the goal line becomes the line to gain as they cannot make another first down (barring a defensive penalty) without actually scoring. In these situations the number of yards is replaced with & goal, i.e. 1st & goal.
Other downs-related terminology is as follows:
In the early 19th Century in rugby union football, the ball became dead in the field of play only by mutual consent of opponents. A player carrying the ball and held by opponents would say, "Held!", and his opponent would say, "Have it down." That is, the ballcarrier would declare himself fairly held, unable to advance, and an opponent would call on him to put the ball down, initiating the scrimmage.
In modern rugby league, this is called a tackle and each team has six tackles to score; if they fail then possession changes over to the other team. The rule was established at four tackles in 1966 and was changed to six tackles in 1972.
In American football, the concept of the act of having the ball down gave rise to "down" as the condition of the player so obligated, and the ball carrier could call for a "down" voluntarily. Although NCAA rules have effectively abolished this (as the ball carrier dropping to the ground immediately ends the play), other codes for North American football, such as the NFL, still allow (as one way for the ball to become dead) for the runner to cry "down". The rule is rarely used, despite having practical advantages over the preferred method of intentional downing, the kneel.
Eventually the rules officially applied the word to include all of the action from the time the ball was put into play (whether by snap or free kick) until it became dead.
The system of downs, in terms of a set number of plays to advance the ball a certain number of yards, were originally devised by Walter Camp and introduced to the game at the college football level in 1880, when Camp was still a player of the game. Camp's original system gave teams three downs to advance the ball five yards or else lose possession of the ball, a proposal meant to reduce sandbagging. Early in the 20th century, as the forward pass was added to the game and kicking rules became more restrictive, a fourth down was added, and the requirement was doubled to 10 yards. The system of downs was introduced to Canadian football in 1903, where the Burnside rules imposed a ten yards in three downs requirement (like Walter Camp's early rules); those criteria remain in Canadian football to the present day.
The term comes from the standard practice that an offensive unit only has three "real" plays before they are expected to punt. While, in theory, a team is allowed a fourth running or passing play, using the fourth down to run or pass is a risky move under most circumstances. If they fail to gain a new first down on a fourth-down play, the opposing team takes possession at the spot where they left off, giving them better field position than if the ball had been punted farther toward the opposing team's end zone. Typically, a team will run or pass on fourth down only if they are trailing late in a close game, are close enough to the first down marker (usually a yard or less) and in the opposing team's territory, or in a certain part of the field where a punt will likely result in a touchback (which will result in a relatively limited net gain of yardage), but just beyond the distance where a field goal is likely to be successful (in the NFL, a missed field goal results in the opposition taking possession at the spot of the unsuccessful kick) - the range at which American football coaches will typically attempt to convert fourth downs where they otherwise would not varies between the opponent's 30- and 45-yard lines, depending on such factors as the kicker's or punter's perceived abilities and the required distance to gain.
Punting following a three-and-out is unlike a turnover on downs. Punting after a three-and-out allows a team the opportunity to set their opposition farther back in field position. On a turnover on downs, there is no punt and the opposing team takes over possession of the ball at the spot of field where the final (third in the Canadian game, fourth in the American game) down ended.
In Canadian football, since there are three downs, the term "two and out" is used in this situation. In the Canadian game, single points can be scored on punts and missed field goals. As a result, Canadian football coaches will never "go for it" simply on account of the ball being on the edge of field goal range - barring extraordinary circumstances (such as trailing by between four and eight points late in the game), teams facing third and relatively long at the edge of field goal range will typically either punt (typically with the intent of putting the ball out of bounds near the opposing goal line as opposed to actually scoring a single point) or attempt a field goal.
After 3 incompletions and facing 4th-and-game