Gridiron Glossary

Do you know your first downs from your fumbles?

BBC Sport Online makes sense of the jargon that will feature in coverage of Super Bowl XXXVI between the St Louis Rams and the New England Patriots.

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Audible: when the quarterback changes the play agreed in the huddle by shouting out a new play at the line of scrimmage.

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Backfield: the area located behind the line of scrimmage, normally occupied by one or two running backs.

Backs: running backs - can be half- or full-backs.

Blitz: a defensive ploy that involves sending additional players towards the line of scrimmage to try to sack the opposingquarterback.

Blocking: the legal obstruction the offensive team uses to prevent defensive players from getting to the ball carrier.

Bomb: a long, looping pass thrown downfield to a sprinting receiver.

Bump-and-run: a defensive tactic that involves hitting a receiver once within 10 yards of the line of scrimmage to slow him down, and then marking him closely to prevent the receiver from catching a pass.

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Down: the basic goal of every team when on offence is to move the ball forward 10 yards at a time. The attacking team has four chances (downs) to gain 10 yards (see first down), thereby earning another set of four chances. If the team fails to make the 10 yards, possession is surrendered.

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End zone: the 10-yard area beyond the goal line at each end of the pitch in which touchdowns are scored.

Extra point: scoring a touchdown earns teams the right to gain another point by kicking the ball through the goalposts - similar to a rugby conversion. A two-point conversion is earned by running or passing the ball into the end zone.

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Field goal: a place kick that passes above the crossbar and between the uprights of the goalpost. Worth three points.

First down: the first of the four chances the offensive team has to gain 10 yards. Once it has advanced 10 yards, it gets a new first down.

Fumble: when a player in possession drops the ball or has it knocked away by a defensive opponent.

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Intentional grounding: a foul called against a quarterback who purposely throws an incomplete forward pass to avoid a sack.

Interception: a pass caught by a defensive player which then gives his team possession.

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Kick-off: kicked by the offensive team's specialist kicker from a tee on the 30-yard line. Used to start the game, the second half and overtime, and to restart play after each score.

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Line of scrimmage: invisible line that extends across the field from which each play begins.

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Offside: a foul punished by a five-yard penalty, committed when any part of a player's body is beyond his line of scrimmage when the ball is snapped.

Overtime: played if a game is tied after four 15-minute quarters. The first team to score wins.

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Personal foul: a flagrant foul punishable by a 15-yard penalty.

Play: attacking ploys, either pre-arranged or called on the field by the quarterback (see audible), which the defensive team try to counter.

Pocket: the quarterback is said to be in the "pocket" when a circle of team-mates (his offensive line) protect him after he has dropped back to pass.

Punt: when the attacking team kicks possession away, usually on fourth down, in order to gain territory before the other team takes the ball.

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Quarterback: a team's offensive mastermind, receives the snap from the centre.

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Receiver: an offensive player whose job it is to catch the ball when it is thrown forward, usually by the quarterback.

Return: carrying the ball after it has been exchanged on a kick-off, punt, interception, or fumble recovery.

Rushing: running with the ball.

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Sack: when one a defensive player tackles the opposing quarterback behind the line of scrimmage, usually preventing a play.

Safety: when an attacking player is tackled in his own end zone with the ball. The defence earns two points and receives a free kick from the offence's 20-yard line.

Snap: when the offensive team's center passes the ball backwards between his legs at the line of scrimmage, either to the quarterback or to be placed for the kicker.

Special Teams: players on a team's kickoff, kickoff return, punt, and punt return units.

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Touchdown: worth six points and scored when a team crosses the opponent's goal line with the ball, catches a pass in their opponent's end zone or recovers a loose ball in the end zone.

Turnover: the involuntary loss of possession during a play, either by a fumble or an interception.

Two-point conversion: an option when a team that just scored a touchdown starts a play at the opposing two-yard line and crosses the goal line to earn two points.

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Wild Card: a team that makes the NFL play-offs by having one of the three best records among non-division winners in its Conference.

For a digest of the rules of the game go to the website listed under 'Internet Links'.