A formation in American football refers to the position players line up in before the start of a down. There are both offensive and defensive formations and many in both categories. Sometimes, formations are referred to as packages.

Offense

At the highest level of play in the NFL and NCAA, the one constant in all formations is the offensive line, consisting of the left and right tackle, left and right guard, and a center. These five positions are often referred to collectively as the "line", and have the primary role of blocking. By rule, there must be two additional players on the line of scrimmage called ends. These players are eligible receivers and may play near the linemen (tight ends) or further away (split end or wide receiver). Most teams play additional players near (but still off) the line of scrimmage to act as extra pass receivers.

Offensive positions

Up to four players can be behind the offensive line, but one is always designated the quarterback (defined as the player who receives the ball from the center). Upon the snap of the ball, the quarterback becomes the ball carrier. The ball carrier has five options:

  • He may keep the ball and run with it.
  • He may hand or pitch the ball sideways or backward (also called a lateral) 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 backward.
  • He may throw a forward pass to an eligible receiver, who then becomes the new ball Carrier. Only one 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 it 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 (which is rare).

The three other backs can be halfbacks (who primarily carry the ball), fullbacks (who mainly block), or they can play near (but not on) the line of scrimmage to act as extra tight ends or wide receivers. A tight end who fills the role as the 4th back is often called an "H-Back", and a wide receiver who fills that role is sometimes known as a "flanker" or a "slot" receiver (depending on where he lines up). Most formations have a "strong" side (the side with the tight end, or the side with more players) and a "weak side" (the side opposite the tight end, or the side with fewer players).

The ends, which may be either wide receivers or tight ends, may catch a passed ball or receive a handoff.

Descriptions and diagrams to display offensive formations typically use the following symbols:

  • QB = quarterback (the player who leads and informs the offense of the plays)
  • C = center (the player who begins the play with a snap on the line and blocks afterward)
  • G = guard (the player who blocks on the line beside the center)
  • T = tackle (the player who blocks on the line beside the guard)
  • TE = tight end (the player who goes out for passes and often blocks on the line)
  • WR = wide receiver (the player who gets assigned a route and must catch the ball when passed to)
  • HB = halfback (the primary ball carrier)
  • FB = fullback (the secondary ball carrier also used for blocking)

Rules

The offense is required to set up a formation before a play, subject to several 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 and 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 can be an eligible receiver. This generally only occurs with the special formations used in kicking and punting situations.
  • The other players not on the line (usually 4 in number) 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" normally refers to the area directly behind the offensive line. 3 of the 4 "backfield" players (i.e., the 3 not receiving the snap from center) may line up as wide receivers if 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 (or more) 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 (unless it is first touched by an eligible receiver, including a deflection by a defensive player), and on a forward pass play, they may not advance downfield (i.e., across the neutral zone) 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 of 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 that 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 (i.e.: with numbers 50-79) to receive a pass.
  • In high school (NFHS), 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 (5 yards plus loss of down). 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 (punt or field goal).
  • The offense must set before the play. All players must take their positions and remain motionless for at least one second before the ball is snapped.