Quarter
Quarterbacks are members of the offensive team and line up directly behind the center, in the middle of the offensive line. Quarterbacks are the leaders of the offensive team, responsible for calling the play in the huddle.
Every play starts with a "snap", an action where the offense's center gives the ball to the quarterback, although occasionally teams will use a "direct snap" (usually as a trick play) to another offensive player.
After receiving the ball, the quarterback either throws a pass or hands it to another offensive player; in some cases, the quarterback will keep the ball in an attempt to run or "scramble" past the defense.
At most levels, but especially at the college and professional level, the quarterback role is one of the most visible and important roles on the team. The quarterback touches the ball on nearly every offensive play and has a great deal of responsibility both in calling plays and making decisions during the play.
While there is liberal substitution at most positions in football based on the play call and to minimize player fatigue, most quarterbacks are on the field for every offensive play leaving only for injury or when the game's outcome is no longer in doubt. Quarterbacks are frequently chosen early in the NFL Draft and often receive much more lucrative contracts than other positions.
As of 2008, players in this position have won more Super Bowl MVP awards (22 of 43) than players at any other position combined.
As the term "quarterback" gained acceptance in the 1930s, it originally referred to the player's position relative to other members of the offensive backfield. Before the emergence of the T-formation in the 1940s, all members of the offensive backfield were legitimate threats to run or pass the ball, and most teams used four offensive backs on every play: a quarterback, two halfbacks, and a fullback.
The quarterback began each play a quarter of the way back, the halfbacks began each play side by side and halfway back, and the fullback began each play the farthest back. Now that most offensive formations have only one or two running backs, the original designations do not mean as much, as the fullback is now usually a lead blocker (technically a halfback), while the halfback or tailback (called such because he stands at the "tail" of the I) lines up behind the fullback.
Traditionally, quarterbacks have been responsible for calling the team's offensive plays based on the defense's formation, or game situation.
For instance, Peyton Manning of the Indianapolis Colts calls all, or nearly all, of his team's plays using his no-huddle offense. In order to choose the proper play, quarterbacks will often spend time rehearsing and studying prearranged plays during their team's practice sessions.
In recent years, the rise of offensive coordinators has led partiality toward a scripted game plan. When the players are set in a formation, the quarterback will start the play by calling out a code word, a number or a combination of the two.
Michael Vick uses his mobility to elude Dwight Freeney, a member of the AFC team at the NFL's 2006 Pro Bowl
Special tactics
If quarterbacks are uncomfortable with the formation the defense is using, they may call an audible change to their play.
In order to do this, the quarterback will yell a special code, like "Blue 42" or "Texas 29", which informs the offense to switch to a specific play or formation.
Also, quarterbacks can "spike" or throw the football at the ground, in order to stop the official game clock. For example, if a team is down by a field goal with only seconds remaining, a quarterback may spike the ball in order to prevent the game clock from running out.
This usually allows the field goal unit to come onto the field, or attempt a final "Hail Mary pass". This is normally done when the opposing team has no timeouts and there is little time left in the game, as it allows a team to burn up the remaining time on the clock without risking a turnover or injury.
Receiving
While quarterbacks are mainly not a factor in terms of receiving forward passes, some trick plays, like the flea flicker, require quarterbacks to catch a lateral by a wide receiver or running back before delivering a forward pass.
In the wildcat formation, a quarterback lines up as a flank receiver who can be used to catch a forward pass. Occasionally, some backup quarterbacks may be used to receive long snaps as a holder for field goal or extra point attempts, as quarterbacks generally have good ball handling skills.
Under NFL rules, if a quarterback lines up under center, he is by definition ineligible and not allowed to receive a forward pass.
While arm power, accuracy, and pocket presence – the ability to successfully operate from within the "pocket" formed by his blockers – are still the most important quarterback virtues, the ability to elude or run past defenders creates an additional threat that allows greater flexibility in the team's passing and running game.
This is generally more successful at the college level. Typically, a quarterback with exceptional quickness will be used in an option offense, which allows the quarterback to either hand the ball off, run it himself, or pitch it to the running back following him at a distance of three yards outside and one yard behind.
In the college game, many schools employ several plays that are designed for the quarterback to run with the ball. Cohen, and Rick Korch, The Football Encyclopedia: The Complete History of Professional Football, From 1892 to the Present (St.