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American Football

American football
Larry Fitzgerald catches TD at 2009 Pro Bowl.jpg
Larry Fitzgerald (in blue) catches a pass while defended by Cortland Finnegan (in red) at the 2009 Pro Bowl
Nicknames Football, gridiron
First played November 6, 1869
New Brunswick, New Jersey, United States
(Princeton vs. Rutgers)
Characteristics
Contact Full-contact
Team members 11 (both teams may freely substitute players between downs)
Type Team sport, ball game
Equipment Football (leather prolate spheroid)
Football helmet
Pads (shoulder and knee)
Venue Football field (rectangular: 120 yards long, 53 1/3 yards wide)
Presence
Country or region Worldwide (most prominent in North America, Europe, and Japan)
Olympic No (demonstrated at the 1932 Summer Olympics)
Part of the American football series on
History of American football

• Origins of American football

Early history of American football
First game
Walter Camp
First pro player
First pro league
Modern history of American football

• Close relations:

Medieval football
Old division football
Rugby football
Association football
Canadian football

Black players in American professional football
Homosexuality in American football
Concussions in American football
Rugby union comparison
Rugby league comparison
Canadian football comparison
Pro Football Hall of Fame
College Football Hall of Fame
Years in American football

NFL season-by-season
College football season-by-season

American football, referred to as football in the United States and Canada, and also known as gridiron, is a sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team with control of the oval-shaped football, attempts to advance down the field by running with or passing the ball, while the team without control of the ball, the defense, aims to stop their advance and take control of the ball for themselves. The offense must advance at least ten yards in four downs, or plays, or else they turn over the football to the opposing team; if they succeed, they are given a new set of four downs. Points are primarily scored by advancing the ball into the opposing team's end zone for a touchdown or kicking the ball through the opponent's goalposts for a field goal. The team with the most points at the end of a game wins.

American football evolved in the United States, originating from the sports of association football and rugby football. The first game of American football was played on November 6, 1869, between two college teams, Rutgers and Princeton, under rules based on the association football rules of the time. During the latter half of the 1870s, colleges playing association football switched to the Rugby Union code, which allowed carrying the ball. A set of rule changes drawn up from 1880 onward by Walter Camp, the "Father of American Football", established the snap, eleven-player teams, and the concept of downs; later rule changes legalized the forward pass, created the neutral zone, and specified the size and shape of the football.


Early history of American football
First game
Walter Camp
First pro player
First pro league
Modern history of American football
Medieval football
Old division football
Rugby football
Association football
Canadian football
NFL season-by-season
College football season-by-season
  • The referee is positioned behind and to the side of the offensive backs. He is charged with oversight and control of the game and is the authority on the score, the down number, and any and all rule interpretations in discussions between the other officials. He announces all penalties and discusses the infraction with the offending team's captain, monitors for illegal hits against the quarterback, makes requests for first-down measurements, and notifies the head coach whenever a player is ejected. He positions himself to the passing arm side of the quarterback. In most games, the referee is responsible for spotting the football prior to a play from scrimmage.
  • The umpire is positioned in the defensive backfield, except in the NFL, where he is positioned lateral to the referee on the opposite side of the formation. He watches play along the line of scrimmage to make sure that no more than 11 offensive players are on the field prior to the snap and that no offensive linemen are illegally downfield on pass plays. He monitors the contact between offensive and defensive linemen and calls most of the holding penalties. The umpire records the number of timeouts taken and the winner of the coin toss and the game score, assists the referee in situations involving possession of the ball close to the line of scrimmage, determines whether player equipment is legal, and dries wet balls prior to the snap if a game is played in rain.
  • The back judge is positioned deep in the defensive backfield, behind the umpire. He ensures that the defensive team has no more than 11 players on the field and determines whether catches are legal, whether field goal or extra point attempts are good, and whether a pass interference violation occurred. The back judge is also responsible for the play clock, the time between each play, when a visible play clock is not used.
  • The head linesman is positioned on one end of the line of scrimmage. He watches for any line-of-scrimmage and illegal use-of-hands violations and assists the line judge with illegal shift or illegal motion calls. The head linesman also rules on out-of-bounds calls that happen on his side of the field, oversees the chain crew and marks the forward progress of a runner when a play has been whistled dead.
  • The side judge is positioned twenty yards downfield of the head linesman. He mainly duplicates the functions of the field judge. On field goal and extra point attempts, he is positioned lateral to the umpire.
  • The line judge is positioned on the end of the line of scrimmage, opposite the head linesman. He or she supervises player substitutions, the line of scrimmage during punts, and game timing. He notifies the referee when time has expired at the end of a quarter and notifies the head coach of the home team when five minutes remain for halftime. In the NFL, the line judge also alerts the referee when two minutes remain in the half. If the clock malfunctions or becomes inoperable, the line judge becomes the official timekeeper.
  • The field judge is positioned twenty yards downfield from the line judge. He monitors and controls the play clock, counts the number of defensive players on the field, and watches for offensive pass interference and illegal use-of-hands violations by offensive players. He also makes decisions regarding catches, recoveries, the ball spot when a player goes out of bounds, and illegal touching of fumbled balls that have crossed the line of scrimmage. On field goal and extra point attempts, the field judge is stationed under the upright opposite the back judge.
  • The center judge is an eighth official used in the top level of college football. He stands lateral to the referee, the same way the umpire does in the NFL. The center judge is responsible for spotting the football after each play, and has many of the same responsibilities as the referee, except announcing penalties.
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Wikipedia

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