Formation (American football)

Offense

Offensive positions

• He may keep the ball and run with it.
• He may hand or pitch the ball sideways or backwards to another player, who then becomes the new ball carrier. Multiple pitches are permitted on a single play, as long as all of them go backwards.
• He may throw a forward pass to an eligible receiver, who then becomes the new ball carrier. Only 1 forward pass is permitted per play. The pass must be thrown from behind the original line of scrimmage, while the receiver can be anywhere on the field. A pass to a receiver who is also behind the line of scrimmage is still a forward pass as long as the pass travels forward. A forward pass is distinct from a pitch, and any number of pitches are permitted before or after a forward pass.
• He may hold the ball for a place-kicker who attempts a field goal.
• He may kick the ball himself, either by punting the ball to the other team, or by attempting a drop-kicked field goal.

• QB = quarterback
• C = center
• G = guard
• T = tackle
• TE = tight end
• WR = wide receiver
• HB = halfback
• FB = fullback

  Rules

• The formation must have at least 7 players on the line of scrimmage. The 7 players are not required to be next to each other, so they may spread out across the width of the field, but this is rare; most offenses place at least 5 players together in a continuous line. Teams may place more than 7 players on the line, but only the player at each end of the line may be an eligible receiver, so generally this only occurs with the special formations used in kicking and punting situations.
• The other players not on the line may be positioned anywhere, but all must be at least 1 yard behind the 7 or more players on the line of scrimmage. The traditional saying is "7 on the line, 4 in the backfield" but this is something of a misnomer, as "backfield" usually refers to the area directly behind the offensive line. 3 of the 4 "backfield" players may line up as wide receivers as long as they are behind the line of scrimmage; these are known as slot receivers if between the ends, and flankers if outside the ends.
• Of the 7 players on the line of scrimmage, all except those at either end of the line are ineligible receivers: these players may not touch or catch a forward pass, and on a forward pass play, they may not advance downfield before the pass crosses the neutral zone. Ineligible receivers may advance freely on a running play or after a pass is thrown. These players typically have uniform numbers in the range 50-79 to indicate they are ineligible.
• In the NFL, players with numbers 50-79 are considered ineligible by default. They must report to the referee if they line up in a position which would normally be considered eligible; failure to do so will result in a penalty to the offense. The referee will relay that information to the defensive captain, and he will generally announce it to spectators as well. After reporting as eligible, those players may line up at any legal position just as if they were normally eligible receivers. Offenses sometimes use this tactic in a short yardage situation to provide extra blocking, and some plays are even designed for a designated player to receive a pass.
• In high school numbers 50-79 are always ineligible, and may not receive. In fact if one of these players bats, muffs, or catches a legal forward pass before it is touched by a defensive player, it is a penalty for illegal touching. Typically you must have 5 players numbered 50-79 on the line of scrimmage, but there are exceptions to this rule when the offense is lined up in scrimmage kick formation.
• The offense must set before the play: all players must take their positions and remain motionless for at least 1 second before the ball is snapped. Typically, after the offense breaks the huddle and walks to the line, the quarterback will call "set" and then begin his regular snap count. The offense is allowed to shift in certain situations and reorganize, but they must again set once they assume new positions. Once set, offensive players may not move until the snap and may not flinch to simulate a snap. A violation is a false start penalty.
• The offense may put one of the 4 backfield players in motion after the set but before the snap. The motion must be either parallel to or away from the line of scrimmage at the snap; certain types of football such as arena football allow forward motion at the snap. In Canadian football, all of the players in the backfield can be in motion, in any direction, at the time of the snap, as long as they have not crossed the line of scrimmage before the snap.

  Defense

Defensive positions

• Defensive lineman : Linemen play at the line of scrimmage, directly across from the offensive line. They are categorized as defensive tackles or defensive ends. The 4-3 defense has 2 tackles and 2 ends; the 3-4 defense has 2 ends and 1 tackle, who is sometimes called a nose tackle to indicate the 3-4. Tackles line up inside and rely on power to stop the run, while ends line up outside and are faster and more athletic to allow them to pursue the quarterback.
• Linebacker : Linebackers are positioned 2 to 4 yards behind the defensive line. The 4-3 defense has 3 linebackers, who are categorized as strong, middle and weak. This is not an indication of strength; it instead refers to the positioning of the linebackers relative to the offense. Strong linebackers line up on the same side as the tight end, weak side away from the tight end. A 3-4 defense will use 4 linebackers, who are indicated by their side and positioning.
• Defensive back : Defensive backs can include cornerbacks, a strong safety and a free safety. Cornerbacks are almost always responsible for defending against the pass, and particularly against wide receivers; often they are the fastest defensive players. Safeties also defend against the pass, matching up on tight ends and backs, but they are positioned in the center of the field to be prepared to stop the run as well.

  Rules