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American football

American football

Overview

American football, known in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Canada
Canada
Canada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean...

 simply as football, and often as Gridiron or Tackle football outside North America, is a competitive team sport
Team sport
Team sport refers to sports that are practiced between opposing teams, where the players interact directly and simultaneously between them to achieve an objective. The objective generally involves teammates facilitating the movement of a ball or similar item in accordance with a set of rules, in...

 known for combining strategy with physical play. The objective of the game is to score points by advancing the ball into the opposing team's end zone
End zone
The end zone is a term used in both Canadian football and American football. The end zone is the area between the end line and goal line bounded by the sidelines. There are two end zones, each being on an opposite side of the field...

. The ball can be advanced by carrying it (a running play) or by throwing it to a teammate (a passing play).
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Encyclopedia

American football, known in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Canada
Canada
Canada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean...

 simply as football, and often as Gridiron or Tackle football outside North America, is a competitive team sport
Team sport
Team sport refers to sports that are practiced between opposing teams, where the players interact directly and simultaneously between them to achieve an objective. The objective generally involves teammates facilitating the movement of a ball or similar item in accordance with a set of rules, in...

 known for combining strategy with physical play. The objective of the game is to score points by advancing the ball into the opposing team's end zone
End zone
The end zone is a term used in both Canadian football and American football. The end zone is the area between the end line and goal line bounded by the sidelines. There are two end zones, each being on an opposite side of the field...

. The ball can be advanced by carrying it (a running play) or by throwing it to a teammate (a passing play). Points can be scored in a variety of ways, including carrying the ball over the opponent's goal line, catching a pass thrown over that goal line, kicking
Placekicker
Placekicker, or simply kicker , is the title of the player in American and Canadian football who is responsible for the kicking duties of field goals, extra points, and, in many cases, kickoffs....

 the ball through the goal posts at the opponent's end zone, or tackling an opposing ball carrier within his end zone. The winner is the team with the most points when the time expires.

American football is closely related to Canadian football
Canadian football
Canadian football is a form of gridiron football played almost exclusively in Canada in which two teams of 12 players each compete for territorial control of a field of play long and wide , attempting to advance a pointed prolate spheroid ball into the opposing team's scoring area...

, but with significant differences
Comparison of Canadian and American football
Canadian and American football are very similar, as both have their origins in rugby, but there are some key differences.-History:Football was introduced to North America in Canada by the British Army garrison in Montreal, which played a series of games with McGill University...

. Both sports originated from rugby football
Rugby football
Rugby football may refer to a number of sports through history descended from a common form of football developed in different areas of the United Kingdom. Today it refers to either rugby league or rugby union.- History :...

. The major forms of football in the United States are collegiate football
College football
College football is American football played by teams of student athletes fielded by American universities, colleges, and military academies. It was the venue through which American football first gained popularity in the United States...

 and professional football
Professional football
Professional Football includes the professional forms of American and Canadian gridiron football. In common usage, it refers to former and existing major football leagues in either country. Currently , there are three major Professional Football leagues in North America: the NFL and the UFL in...

. There have been numerous major professional football leagues in the U.S.; the two currently in existence are the National Football League
National Football League
The National Football League is the largest professional American football league in the world. It was formed by eleven teams in 1920 as the American Professional Football Association, with the league changing its name to the National Football League in 1922. The league currently consists of...

 (NFL) and the United Football League.

The sport is also played outside the United States. National professional and collegiate leagues exist in United Kingdom
British American Football League
The British American Football League is the United Kingdom's primary American Football league. It was formerly known as the British Senior League until 2005....

, Germany
German Football League
The German football League is the elite bundesliga for American football in Germany.- League set-up :The GFL is partitioned into north and south conferences, each with six teams. In each conference, every team plays against every other team of the own conference, both at home and away...

, Italy
Italy
Italy , officially the Italian Republic , is a country located on the Italian Peninsula in Southern Europe and on the two largest islands in the Mediterranean Sea, Sicily and Sardinia. Italy shares its northern, Alpine boundary with France, Switzerland, Austria and Slovenia...

, Switzerland
Switzerland
Switzerland , officially the Swiss Confederation , is a federal republic consisting of 26 states named cantons, with Bern as the seat of the federal authorities...

, Finland
Vaahteraliiga
The Vaahteraliiga is the highest level of American football in Finland played under American Football Association of Finland. The winner of the Vaahteraliiga is the Finnish champion. The Vaahteraliiga season is played in summer, with a schedule usually from May to September.The first season of the...

, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...

, Japan
X-League
The X-League is a semi-professional American football league in Japan. It was founded in 1971 as the Japan American Football League. It changed its name to the X-league in 1997. There are four division between which there is promotion and relegation. Teams in the four-tier league are split into...

, Mexico
Mexican College Football
The National Student Organization of American Football, is a Mexican college football league....

, Israel
Israel
Israel officially the State of Israel , is a developed state in Western Asia located on the eastern shore of the Mediterranean Sea. It borders Lebanon in the north, Syria in the northeast, Jordan in the east, and Egypt on the southwest, and contains geographically diverse features within its...

, Spain
LNFA
Liga Nacional de Fútbol Americano is the name of the top american football league which operates in Spain. It was founded in 1995 after the merge of several previous Spanish competitions....

, Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.3 million people in Central Europe. It borders both Germany and the Czech Republic to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west...

, and several Pacific Island nations.

History



Primitive forms of rugby
Rugby football
Rugby football may refer to a number of sports through history descended from a common form of football developed in different areas of the United Kingdom. Today it refers to either rugby league or rugby union.- History :...

, then all covered by the name "football", were being played in the USA as far back as the 1840s, at Harvard
Harvard University
Harvard University is a private university located in Cambridge, Massachusetts and a member of the Ivy League. Founded in 1636 by the colonial Massachusetts legislature, Harvard is the oldest institution of higher learning in the United States and currently comprises ten separate academic units...

, Yale
Yale University
Yale University is a private research university in New Haven, Connecticut, and a member of the Ivy League. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States. Yale has produced many notable alumni, including five...

 and Princeton
Princeton University
Princeton University a private university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League and is considered one of the Colonial Colleges....

, stemming partly from Americans who had been educated in English schools. The history of American football can be traced to early versions of rugby football
Rugby football
Rugby football may refer to a number of sports through history descended from a common form of football developed in different areas of the United Kingdom. Today it refers to either rugby league or rugby union.- History :...

 and association football (called soccer in the United States). Both games have their origins in varieties of football
Football
Football is the name of several similar team sports, all of which involve kicking a ball with the foot in an attempt to score a goal. The most popular of these sports worldwide is association football, more commonly known as just "football" or "soccer"...

 played in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...

 in the mid-19th century, in which a ball is kicked at a goal
Goal (sport)
Goal refers to a method of scoring in many sports. It can also refer to the physical structure or area of the playing surface in which a score is made....

 and/or run over a line.

American football resulted from several major divergences from rugby football
Rugby football
Rugby football may refer to a number of sports through history descended from a common form of football developed in different areas of the United Kingdom. Today it refers to either rugby league or rugby union.- History :...

, most notably the rule changes instituted by Walter Camp
Walter Camp
Walter Chauncey Camp was a sports writer and American football coach known as the "Father of American Football". With John Heisman, Amos Alonzo Stagg, Glenn Scobey Warner, Fielding H...

, considered the "Father of American Football". Among these important changes were the introduction of the line of scrimmage
Line of scrimmage
In American and Canadian football a line of scrimmage is an imaginary transverse line crossing the football field across its narrower dimension, beyond which a team cannot cross until the next play has begun...

 and of down-and-distance rules. In the late 19th and early 20th centuries, game play developments by college coaches such as Eddie Cochems
Eddie Cochems
Edward B. "Eddie" Cochems was the first American football coach to build an offense around the forward pass.-Father of the Forward Pass:...

, Amos Alonzo Stagg
Amos Alonzo Stagg
Amos Alonzo Stagg was an American collegiate coach in multiple sports, primarily football, and an overall athletic pioneer. He was born in West Orange, New Jersey, and attended Phillips Exeter Academy...

, Knute Rockne
Knute Rockne
Knute Kenneth Rockne was an American football player and is regarded as one of the greatest coaches in college football history. His biography at the College Football Hall of Fame calls him "American football's most-renowned coach." He was a native Norwegian, and was trained as a chemist at Notre...

, and Glenn "Pop" Warner
Glenn Scobey Warner
Glenn Scobey Warner was an American football coach, also known as Pop Warner. During his 44-year career as a head coach , Warner had 319 major NCAA college football wins. The 319 wins listed does not include 18 wins at Iowa State University...

 helped take advantage of the newly introduced forward pass
Forward pass
In several forms of football a forward pass is when the ball is thrown in the direction of the opponent's end line.-American and Canadian Football:...

.

The popularity of collegiate football
College football
College football is American football played by teams of student athletes fielded by American universities, colleges, and military academies. It was the venue through which American football first gained popularity in the United States...

grew as it became the dominant version of the sport for the first half of the twentieth century. Bowl game
Bowl game
In the United States, a bowl game is commonly considered to refer to one of a number of post-season college football games. Prior to 2002, bowl game statistics were not included in players' career totals and the games were mostly considered to be exhibition games involving a payout to participating...

s, a college football tradition, attracted a national audience for collegiate teams. Bolstered by fierce rivalries, college football still holds widespread appeal in the US.

The origin of professional football
Professional football
Professional Football includes the professional forms of American and Canadian gridiron football. In common usage, it refers to former and existing major football leagues in either country. Currently , there are three major Professional Football leagues in North America: the NFL and the UFL in...

can be traced back to 1892, with William "Pudge" Heffelfinger's
William Heffelfinger
William "Pudge" Walter Heffelfinger was an American football player and considered the first to play professionally....

 $500 contract to play in a game for the Allegheny Athletic Association
Allegheny Athletic Association
The Allegheny Athletic Association was an athletic club in Allegheny, Pennsylvania that fielded the first ever professional American football player and later the first fully professional football team. The organization was founded in 1890 as a regional athletic club.-History:The Allegheny team...

 against the Pittsburgh Athletic Club. The first Professional "league" was the Ohio League
Ohio League
The Ohio League was an informal association of American football clubs active between 1903 and 1919. As the name implied, its teams were based in Ohio, and is the direct predecessor to the National Football League of today....

, formed in 1903, and the first Professional Football championship game was between the Buffalo Prospects and the Canton Bulldogs
Canton Bulldogs
The Canton Bulldogs was one of the first American Professional Football teams, and was based in Canton, Ohio. They played in the Ohio League from 1903 to 1906 and 1911 to 1919, and in the National Football League from 1920 to 1923 and 1925 to 1926. The Bulldogs won the 1922 and 1923 NFL championships...

 in 1919. In 1920, the American Professional Football Association was formed. The first game was played in Dayton, Ohio
Dayton, Ohio
Dayton is a city in and the county seat of Montgomery County, Ohio, United States, in the southwestern part of the state. The population was 166,179 at the 2000 census. The Dayton Metropolitan Statistical Area had a population of 848,153 in the 2000 census. Dayton is the fourth largest...

 on October 3, 1920 with the host Triangles
Dayton Triangles
The Dayton Triangles were an original franchise of the American Professional Football Association in 1920. The Triangles were based in Dayton, Ohio, and took their nickname from their home field, Triangle Park, which was located at the confluence of the Great Miami and Stillwater Rivers in north...

 defeating the Columbus Panhandles
Columbus (NFL)
The Columbus Panhandles were a professional football team from Columbus, Ohio who played in the "Ohio League" and later the American Professional Football Association, later renamed the National Football League...

 14–0. The league changed its name to the National Football League
National Football League
The National Football League is the largest professional American football league in the world. It was formed by eleven teams in 1920 as the American Professional Football Association, with the league changing its name to the National Football League in 1922. The league currently consists of...

 (NFL) two years later, and eventually became the major league
Major professional sports leagues of the United States and Canada
Major professional sports league, or simply major league, is a term used in Canada and the United States for the highest professional competitions in team sports...

 of American football. Initially a sport of Midwestern industrial towns in the United States, professional football eventually became a national phenomenon. Football's increasing popularity is usually traced to the 1958 NFL Championship Game
NFL Championship Game, 1958
The 1958 National Football League Championship Game was played on December 28, 1958 at Yankee Stadium in New York City. It was the first ever National Football League game to go into sudden death overtime. The final score was Baltimore Colts 23, New York Giants 17. The game has since become widely...

, a contest that has been dubbed the "Greatest Game Ever Played". A rival league to the NFL, the American Football League
American Football League
The American Football League was a major Professional Football league that operated from 1960 until 1969, when it merged with the established National Football League . The upstart AFL operated in direct competition with the more established NFL throughout its existence...

 (AFL), began play in 1960; the pressure it put on the senior league led to a merger between the two leagues and the creation of the Super Bowl
Super Bowl
The Super Bowl is the championship game of the National Football League, the premier association of professional American football. In most years, the Super Bowl is the most-watched American television broadcast. Many popular singers and musicians have performed during the event’s pre-game and...

, which has become the most watched television event in the United States on an annual basis.

Field and players


American football is played on a field . The longer boundary lines are sidelines, while the shorter boundary lines are end lines. Sidelines and end lines are out of bounds. Near each end of the field is a goal line; they are apart. A scoring area called an end zone
End zone
The end zone is a term used in both Canadian football and American football. The end zone is the area between the end line and goal line bounded by the sidelines. There are two end zones, each being on an opposite side of the field...

extends beyond each goal line to each end line. The end zone includes the goal line but not the end line. While the playing field is effectively flat, it is common for a field to be built with a slight crown—with the middle of the field higher than the sides—to allow water to drain from the field.

Yard lines cross the field every , and are numbered every 10 yards from each goal line to the 50-yard line, or midfield (similar to a typical rugby league
Rugby league
Rugby league football is a full-contact form of football, played with a prolate spheroid ball by two teams of thirteen players on a rectangular grass field. Rugby league is one of the two codes of rugby football, the other being rugby union...

 field). Two rows of short lines, known as inbounds lines or hash marks, run at 1-yard (91.4 cm) intervals perpendicular to the sidelines near the middle of the field. All plays start with the ball on or between the hash marks. Because of the arrangement of the lines, the field is occasionally referred to as a gridiron.

At the back of each end zone are two goalposts (also called uprights) connected by a crossbar from the ground. For high skill levels, the posts are apart. For lower skill levels, these are widened to .

Each team has 11 players on the field at a time. However, teams may substitute for any or all of their players, if time allows, during the break between plays. As a result, players have very specialized roles, and, sometimes (although rarely) almost all of the (at least) 46 active players on an NFL team will play in any given game. Thus, teams are divided into three separate units: the offense
American football positions
In American football, each team has eleven players on the field at one time. Because the rules allow unlimited substitution between plays, however, the types of players on the field for each team differ depending on the situation...

, the defense
American football positions
In American football, each team has eleven players on the field at one time. Because the rules allow unlimited substitution between plays, however, the types of players on the field for each team differ depending on the situation...

 and the special teams.

Start of halves


Similarly to association football, the game begins with a coin toss
Coin flipping
Coin flipping or coin tossing is the practice of throwing a coin in the air to resolve a dispute between two parties or otherwise choose between two alternatives...

 to determine which team will kick off to begin the game and which goal each team will defend. The options are presented again to start the second half; the choices for the first half do not automatically determine the start of the second half. The referee conducts the coin toss with the captains (or sometimes coaches) of the opposing teams. The team that wins the coin toss has three options:
  1. They may choose whether to kick or receive the opening kickoff.
  2. They may choose which goal to defend.
  3. They may choose to defer the first choice to the other team and have first choice to start the second half.

Whatever the first team chooses, the second team has the option on the other choice (for example, if the first team elects to receive at the start of the game, the second team can decide which goal to defend).

At the start of the second half, the options to kick, receive, or choose a goal to defend are presented to the captains again. The team which did not choose first to start the first half (or which deferred its privilege to choose first) now gets first choice of options.

Game duration


A standard football game consists of four 15-minute quarters (12-minute quarters in high-school football and often shorter at lower levels), with a 12 minute half-time
Half-time
In some team sports such as association football and rugby, matches are played in two halves. Half-time is the name given to the interval between the two halves of the match. Typically, after half-time teams swap ends of the field of play, in order to reduce any advantage that may be gained from...

 intermission after the second quarter. The clock stops after certain plays; therefore, a game can last considerably longer (often more than three hours in real time), and if a game is broadcast on television
Television
Television is a widely used telecommunication medium for transmitting and receiving moving images, either monochromatic or color, usually accompanied by sound. "Television" may also refer specifically to a television set, television programming or television transmission...

, TV timeouts
Television timeout
A television timeout , is a break in a television program to allow television advertisements to be shown. This has the advantage of allowing the networks to take an advertising break without causing viewers to miss part of the action....

 are taken at certain intervals of the game to broadcast commercials
Advertising
Advertising is a form of communication used to influence individuals to purchase products or services or support political candidates or ideas. Frequently it communicates a message that includes the name of the product or service and how that product or service could potentially benefit the consumer...

 outside of game action. If an NFL game is tied after four quarters, the teams play an additional period lasting up to 15 minutes. In an NFL overtime game, the first team that scores wins, even if the other team does not get a possession; this is referred to as sudden death. In a regular-season NFL game, if neither team scores in overtime, the game is a tie. In an NFL playoff game, additional overtime periods are played, as needed, to determine a winner. College overtime rules are more complicated and are described in Overtime (sport)
Overtime (sports)
Overtime is an additional period of play specified under the rules of a sport to bring the game to a decision and avoid declaring the contest a tie or draw...

.





Advancing the ball


Advancing the ball in American football resembles the six-tackle rule and the play-the-ball in rugby league
Rugby league
Rugby league football is a full-contact form of football, played with a prolate spheroid ball by two teams of thirteen players on a rectangular grass field. Rugby league is one of the two codes of rugby football, the other being rugby union...

. The team that takes possession of the ball (the offense) has four attempts, called downs, in which to advance the ball at least toward their opponent's (the defense's) end zone. When the offense succeeds in gaining at least 10 yards, it gets a first down, meaning the team has another set of four downs to gain yet another 10 yards or to score. If the offense fails to gain a first down (10 yards) after 4 downs, the other team gets possession of the ball at the point where the fourth down ended, beginning with their first down to advance the ball in the opposite direction.

Except at the beginning of halves and after scores, the ball is always put into play by a snap
Snap (football)
A snap starts each American football and Canadian football play from scrimmage.-Action:...

. Offensive players line up facing defensive players at the line of scrimmage
Line of scrimmage
In American and Canadian football a line of scrimmage is an imaginary transverse line crossing the football field across its narrower dimension, beyond which a team cannot cross until the next play has begun...

(the position on the field where the play begins). One offensive player, the center
Center (American football)
Center is a position in American football and Canadian football . The center is the innermost lineman of the offensive line on a football team's offense...

, then passes (or "snaps") the ball backwards between his legs to a teammate behind him, usually the quarterback
Quarterback
Quarterback is a position in American and Canadian football. 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...

.

Players can then advance the ball in two ways:
  1. By running with the ball, also known as rushing
    Rush (American football)
    In American football, rushing has two different meanings.-Offense:The first is an action taken by the offensive team that means to advance the ball by running, as opposed to passing. A run is technically any play that does not involve a forward pass. It is usually done by the running back, after...

    .
  2. By throwing the ball to a teammate, known as a forward pass
    Forward pass
    In several forms of football a forward pass is when the ball is thrown in the direction of the opponent's end line.-American and Canadian Football:...

    or as passing the football. The forward pass is a key factor distinguishing American and Canadian football from other football sports. The offense can throw the ball forward only once during a down and only from behind the line of scrimmage. The ball can be thrown, pitched, handed-off, or tossed sideways or backwards at any time.


A down ends, and the ball becomes dead, after any of the following:
  • The player with the ball is forced to the ground (a tackle
    Tackle (football move)
    Most forms of football have a move known as a tackle. The primary purposes of tackling is to disposses an opponent of the ball, to stop the player from gaining ground towards goal or to stop them from carrying out what they intend....

    ) or has his forward progress halted by members of the other team (as determined by an official
    Official (American football)
    In American football, an official is a person who has responsibility in enforcing the rules and maintaining the order of the game.During professional and college football games, seven officials operate on the field...

    ).
  • A forward pass flies beyond the dimensions of the field (out of bounds
    Out of bounds
    Out of bounds is the area outside the boundaries of a sport's field of playOut of Bounds can also refer to:* Similarly, in platform gaming, the term out of bounds is used when a character moves outside the intended playing field, usually due to a glitch.* Out of Bounds , an award winning...

    ) or touches the ground before it is caught. This is known as an incomplete pass
    Incomplete pass
    An incomplete pass is a term in American football which means that a legal forward pass hits the ground before a player on either team gains possession. For example, if the quarterback throws the ball to one of his wide receivers, and the receiver either does not touch it or tries to catch it...

    . The ball is returned to the most recent line of scrimmage for the next down.
  • The ball or the player with the ball goes out of bounds.
  • A team scores.


Officials blow a whistle to notify players that the down is over.

Before each down, each team chooses a play
Play from scrimmage
A play from scrimmage is the activity of the games of Canadian football and American football during which one team tries to advance the ball or to score, and the other team tries to stop them or take the ball away. Once a play is over, and before the next play starts, the football is considered...

, or coordinated movements and actions, that the players should follow on a down. Sometimes, downs themselves are referred to as "plays."

Change of possession


The offense maintains possession of the ball unless one of the following things occurs:
  • The team fails to get a first down— i.e., in four downs they fail to move the ball past a line 10 yards ahead of where they got their last first down (it is possible to be downed behind the current line of scrimmage, losing "yardage"). The defensive team takes over the ball at the spot where the 4th-down play ends. A change of possession in this manner is commonly called a turnover on downs
    Turnover on downs
    In American American football, a turnover on downs occurs when a team fails to convert a fourth down into a first down by gaining the required yardage....

    , but is not credited as a defensive "turnover" in official statistics. Instead, it goes against the offense's 4th down efficiency percentage.
  • The offense scores a touchdown or field goal. The team that scored then kicks the ball to the other team in a special play called a kickoff
    Kickoff (American football)
    A kickoff is a method of starting a drive in American football or Canadian football.- Award :A kickoff occurs at the start of each half and before each overtime . It is also traditionally decided by a coin toss at the beginning of each game carried out by the referee. The visiting team captain...

    .
  • The offense punts the ball to the defense. A punt
    Punt (football)
    A punt in some codes of football, especially American football, rugby league and rugby union, is performed when the ball is kicked without letting it hit the ground first — in contrast to a drop kick...

    is a kick in which a player drops the ball and kicks it before it hits the ground. Punts are nearly always made on fourth down (though see quick kick
    Quick kick
    In American football and Canadian football, a quick kick is any punt made under conditions such that the opposing team "should not" expect a punt. Typically this has been a kick from scrimmage from a formation that is, or resembles, one usually used other than for punting, or at least not...

    ), when the offensive team does not want to risk giving up the ball to the other team at its current spot on the field (through a failed attempt to make a first down) and feels it is too far from the other team's goal posts to attempt a field goal.
  • A defensive player catches a forward pass. This is called an interception
    Interception (football)
    An interception or intercept is a move in many forms of football, including Canadian and American football football, as well as rugby league, rugby union, Australian rules football and Gaelic football, and involves a pass being cut off by an opposition player who usually gains possession for their...

    , and the player who makes the interception can run with the ball until he is tackled, forced out of bounds, or scores.
  • An offensive player drops the ball (a fumble
    Fumble
    A fumble in American and Canadian football is when a player, who has possession and control of the ball, drops the ball. By rule, it is any act other than passing, kicking or successful handing that results in loss of player possession. A fumble may be forced by a defensive player who either grabs...

    ) and a defensive player picks it up. As with interceptions, a player recovering a fumble can run with the ball until tackled, forced out of bounds, or scores. Backward passes that are not caught do not cause the down to end like incomplete forward passes do; instead the ball is still live as if it had been fumbled. Lost fumbles and interceptions are together known as turnovers
    Turnover (football)
    In American football, a turnover is when the team with the ball loses possession of the ball, which is then gained by the other team. The two events that are offically classified as "turnovers" are fumbles or interceptions .The term "turnover" is also...

    .
  • The offensive team misses a field goal attempt. The defensive team gets the ball at the spot where the previous play began (or, in the NFL, at the spot of the kick). If the unsuccessful kick was attempted from within of the end zone, the other team gets the ball at its own 20 yard line (that is, 20 yards from the end zone). If a field goal is missed or blocked and the ball remains in the field of play, a defensive player may pick up the ball and attempt to advance it.
  • While in his own end zone, an offensive ball carrier is tackled, forced out of bounds, loses the ball out of bounds, or the offense commits certain fouls. This fairly rare occurrence is called a safety
    Safety (football score)
    A safety or safety touch is a type of score in American football and Canadian football and is worth two points . In American football, it is the only means by which a team not in possession of the football can score points...

    .
  • An offensive ball carrier fumbles the ball forward into the opposing end zone, and then the ball goes out of bounds. This extremely rare occurrence leads to a touchback
    Touchback
    In American football, a touchback is a ruling which is made and signaled by the referee when the ball crosses into or through the end zone not in control of the team which put it into play. A touchback is not a play, but a result of events that may occur during a play...

    , with the ball going over to the opposing team at their 20 yard line (Note that touchbacks during non-offensive special teams plays, such as punts and kickoffs, are quite common).

Scoring


A team scores points by the following plays:
  • A touchdown
    Touchdown
    A touchdown is the term for scoring American and Canadian football.-Description:To score a touchdown, one team must take the football into the opposite end zone. This can be done by rushing, in which the ball carrier carries the football forward into the end zone. It can also be done by passing,...

    (TD) is worth 6 points. It is scored when a player runs the ball into or catches a pass in his opponent's end zone. A touchdown is analogous to a try
    Try
    A try is the major way of scoring points in rugby league and rugby union football. A try is scored by grounding the ball in the opposition's in-goal area...

     in rugby. Unlike rugby, a player does not have to touch the ball to the ground to score; a touchdown is scored any time a player has possession of the ball while the ball is on or beyond the opponents' goal line (or the plane above it).
    • After a touchdown, the scoring team attempts a try
      Try (American Football)
      A try is a scrimmage down which is neither timed nor numbered, awarded to a team which has just scored a 6 point touchdown, from close to their opponent's goal line . The try allows either team to score an additional 1 or 2 points...

      (which is also analogous to the conversion in rugby). The ball is placed at the other team's line (the line in the NFL). The team can attempt to kick it over the crossbar and through the goal posts in the manner of a field goal for 1 point (an extra point
      Convert
      The Convert or Try, in American and Canadian football, is a one scrimmage down played immediately after a touchdown during which the scoring team is allowed to attempt to score an extra one point by kicking, or two points by touchdown...

      or point-after touchdown (PAT)), or run or pass it into the end zone in the manner of a touchdown for 2 points (a two-point conversion
      Two-point conversion
      In American and Canadian football, a two-point conversion is a play a team attempts instead of kicking a one-point convert immediately after it scores a touchdown...

      ). In college football, if the defense intercepts or recovers a fumble during a one or two point conversion attempt and returns it to the opposing end zone, the defensive team is awarded the two points.
  • A field goal
    Field goal (football)
    A field goal in U.S. football and Canadian football is a goal that may be scored during general play .A field goal may be scored by a placekick or the now very rare drop kick...

    (FG) is worth 3 points, and it is scored by kicking the ball over the crossbar and through the goal posts (uprights). Field goals may be placekicked (kicked when the ball is held vertically against the ground by a teammate) or drop-kicked
    Drop kick
    A drop kick is a type of kick in various codes of football. It involves a player dropping the ball and then kicking it when it bounces off the ground. It contrasts to a punt, wherein the player kicks the ball without letting it hit the ground first....

     (extremely uncommon in the modern game, with only two successes in sixty-plus years in the NFL). A field goal is usually attempted on fourth down instead of a punt when the ball is close to the opponent's goal line, or, when there is little or no time left to otherwise score.
  • A safety
    Safety (football score)
    A safety or safety touch is a type of score in American football and Canadian football and is worth two points . In American football, it is the only means by which a team not in possession of the football can score points...

    , worth 2 points, is scored by the opposing team when the team in possession at the end of a down is responsible for the ball becoming dead behind its own goal line. For instance, a safety is scored by the defense if an offensive player is tackled, goes out of bounds, or fumbles the ball out of bounds in his own end zone. Safeties are relatively rare. Note that, though even more rare, the team initially on offense during a down can score a safety if a player of the original defense gains possession of the ball in front of his own goal line and then carries the ball or fumbles it into his own end zone where it becomes dead. However, if the ball becomes dead behind the goal line of the team in possession and its opponent is responsible for the ball being there (for instance, if the defense intercepts a forward pass in its own end zone and the ball becomes dead before the ball is advanced out of the end zone) it is a touchback: no points are scored and the team last in possession keeps possession with a first down at its own 20 yard line. In amateur football, in the extremely rare instance that a safety is scored on a try, it is worth only 1 point.

Kickoffs and free kicks


Each half begins with a kickoff
Kickoff (American football)
A kickoff is a method of starting a drive in American football or Canadian football.- Award :A kickoff occurs at the start of each half and before each overtime . It is also traditionally decided by a coin toss at the beginning of each game carried out by the referee. The visiting team captain...

. Teams also kick off after scoring touchdowns and field goals. The ball is kicked using a kicking tee from the team's own line in the NFL and college football (as of the 2007 season). The other team's kick returner tries to catch the ball and advance it as far as possible. Where he is stopped is the point where the offense will begin its drive, or series of offensive plays. If the kick returner catches the ball in his own end zone, he can either run with the ball, or elect for a touchback
Touchback
In American football, a touchback is a ruling which is made and signaled by the referee when the ball crosses into or through the end zone not in control of the team which put it into play. A touchback is not a play, but a result of events that may occur during a play...

by kneeling in the end zone, in which case the receiving team then starts its offensive drive from its own 20 yard line. A touchback also occurs when the kick goes out-of-bounds in the end zone. A kickoff that goes out-of-bounds anywhere other than the end zone before being touched by the receiving team is a foul, and the ball will be placed where it went out of bounds or from the kickoff spot, depending on which is more advantageous to the opposite team. Unlike with punts, once a kickoff goes 10 yards and the ball has hit the ground, it can be recovered by the kicking team. A team, especially one who is losing, can try to take advantage of this by attempting an onside kick
Onside kick
Onside kicks is a term used in American and Canadian football for types of kick used at a kickoff or other free kick, or scrimmage kick or other kick during play, in which the ball is kicked favorably for the kicking team to avoid giving away the ball...

. Punts and turnovers in the end zone can also end in a touchback
Touchback
In American football, a touchback is a ruling which is made and signaled by the referee when the ball crosses into or through the end zone not in control of the team which put it into play. A touchback is not a play, but a result of events that may occur during a play...

.

After safeties, the team that gave up the points must free kick the ball to the other team from its own 20 yard line.

Penalties


Fouls (a type of rule violation) are punished with penalties against the offending team. Most penalties result in moving the football towards the offending team's end zone. If the penalty would move the ball more than half the distance towards the offender's end zone, the penalty becomes half the distance to the goal instead of its normal value.

Most penalties result in replaying the down. Some defensive penalties give the offense an automatic first down. Conversely, some offensive penalties result in loss of a down (loss of the right to repeat the down). If a penalty gives the offensive team enough yardage to gain a first down, they get a first down, as usual.

If a foul occurs during a down, an official throws a yellow penalty flag
Penalty flag
The penalty flag is a yellow cloth used in several field sports including American football and lacrosse by game officials to identify and sometimes mark the location of penalties or infractions that occur during regular play...

 near the spot of the foul. When the down ends, the team that did not commit the foul has the option of accepting the penalty, or declining the penalty and accepting the result of the down.

Variations


Variations on these basic rules exist, particularly touch
Touch football (American)
Touch football is a version of American football usually played by amateurs on a recreational basis in which the players "tackle" the individual carrying the ball only by touching him with one or two hands, based on whether one is playing the one-hand touch or two-hand touch variety, as opposed to...

 and flag football
Flag football
Flag football is a version of American football that is popular worldwide. The basic rules of the game are similar to those of the mainstream game , but instead of tackling players to the ground, the defensive team must remove a flag or flag belt from the ball carrier to end a down...

, which are designed as non-contact or limited-contact alternatives to the relative violence
Violence
Violence is the expression of physical or verbal force against self or other, compelling action against one's will on pain of being hurt. Variant uses of the term refer to the destruction of non-living objects . Worldwide, violence is used as a tool of manipulation and also is an area of concern...

 of regular American football. In touch and flag football, tackling is not permitted. Offensive players are "tackled" when a defender tags them or removes a flag from their body, respectively. Both of these varieties are played mainly in informal settings such as intramural
Intramural sports
Intramural sports or intramurals are recreational sports organized within a set geographic area. The term derives from the Latin words intra muros meaning within walls, and was used to indicate sports matches and contests that took place among teams from "within the walls" of an ancient city...

 or youth games. Another variation is "wrap", where a player is "tackled" when another player wraps his arms around the ball carrier. Professional, intercollegiate, and varsity-level high school football invariably use the standard tackling rules.

Another variation is with the number of players on the field. In sparsely populated areas, it is not uncommon to find high school football teams playing nine-man football
Nine-man football
Nine-man football is a type of American football played by high schools that are too small to play the usual eleven-man game. As of 2007, Minnesota, North Dakota and South Dakota had nine man football....

, eight-man football
Eight-man football
Eight-man football is a type of American football, generally played by small high schools. Rules and formations vary greatly among states and even among different organizations, but the one constant is eight players from each team on the field at one time, as opposed to eleven-man football, which...

 or six-man football
Six-man football
Six-man football is a variant of high school American football that is played with six players per team, instead of 11.-History:Six-man football was developed in 1934 by Chester High School coach Stephen Epler as an alternative means for small high schools to field a football team during the Great...

. Players often play on offense as well as defense. The Arena Football League
Arena Football League
The Arena Football League was founded in 1987 as an indoor American football by Jim Foster. It was played indoors on a smaller field than American football, resulting in a faster-paced and higher-scoring game...

 is a league that plays eight-man football, but also plays indoors and on a much smaller playing surface with rule changes to encourage a much more offensive game.

Another variation often played by American children is called Catch and Run. In this game, the children split into two teams and line up at opposite sides of the playing field. One side throws the ball to the other side. If the opposing team catches the ball, that player tries to run to the throwing teams touchdown without being tagged/tackled. If no one catches the ball or if the player is tagged/tackled, then that team has to throw the ball to the opposing team. This repeats until the game (or recess period) is deemed over.

Players


Most football players have highly specialized roles. At the college and NFL levels, most play only offense or only defense.

Offense

  • The offensive line
    American football positions
    In American football, each team has eleven players on the field at one time. Because the rules allow unlimited substitution between plays, however, the types of players on the field for each team differ depending on the situation...

    (OL) consists of five players whose job is to protect the passer and clear the way for runners by blocking members of the defense. The lineman in the middle is the Center. Outside the Center are the Guards, and outside them are the Tackles. Except for the center, who snaps the ball to one of the backs, offensive linemen generally do not handle the ball.
  • The quarterback
    Quarterback
    Quarterback is a position in American and Canadian football. 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...

    (QB) receives the snap from the center on most plays. He then hands or tosses it to a running back, throws it to a receiver or runs with it himself. The quarterback is the leader of the offense and calls the plays that are signaled to him from the sidelines.
  • Running back
    Running back
    A running back is the position of a player on an American or Canadian football team who usually lines up in the offensive backfield...

    s
    (RB) line up behind or beside the QB and specialize in running with the ball. They also block, catch passes and, on rare occasions, pass the ball to others or even receive the snap. If a team has two running backs in the game, usually one will be a halfback
    Halfback (American football)
    A halfback, sometimes referred to as a tailback, is an offensive position in American football, which lines up in the backfield and generally is responsible for carrying the ball on run plays.-Early offensive backfields:...

    (HB) (or tailback (TB)), who is more likely to run with the ball, and the other will usually be a fullback
    Fullback (American football)
    In American football, a fullback is a position in the offensive backfield. Traditionally, the duties of a fullback are split between power running and blocking for the quarterback on passing plays, and the running back on running plays....

    (FB), who is more likely to block.
  • Wide receiver
    Wide receiver
    A wide receiver is an offensive position in American and Canadian football, and is the key player in most of the passing plays. Only players in the backfield or the ends on the line are eligible to catch a forward pass. The two players who begin play at the ends of the offensive line are eligible...

    s
    (WR) line up near the sidelines. They specialize in catching passes, though they also block for running plays or downfield after another receiver makes a catch.
  • Tight end
    Tight end
    The tight end is a position in American football on the offensive team. The tight end is sometimes the last man on the offensive line, but has a slightly different build and, in some cases, a different role than other linemen...

    s
    (TE) line up outside the offensive line. They can either play like wide receivers (catch passes) or like offensive linemen (protect the QB or create spaces for runners). Sometimes an offensive lineman takes the tight end position and is referred to as a tackle eligible.


At least seven players must line up on the line of scrimmage on every offensive play. The other players may line up anywhere behind the line. The exact number of running backs, wide receivers and tight ends may differ on any given play. For example, if the team needs only 1 yard, it may use three tight ends, two running backs and no wide receivers. On the other hand, if it needs 20 yards, it may replace all of its running backs and tight ends with wide receivers.

Defense


In contrast to members of the offense, the rules of professional football (NFL Rulebook) and American college football NCAA Rulebook) do not specify starting position, movement, or coverage zones for members of the defensive team, except that they must be in the defensive zone at the start of play. The positions, movements and responsibilities of all defensive players are assigned by the team by selection of certain coverages, or patterns of placement and assignment of responsibilities. The positional roles are customary. These roles have varied over the history of American football. The following are customary defensive positions used in many coverages in modern American football.
  • The defensive line
    American football positions
    In American football, each team has eleven players on the field at one time. Because the rules allow unlimited substitution between plays, however, the types of players on the field for each team differ depending on the situation...

    consists of three to six players who line up immediately across from the offensive line. They try to occupy the offensive linemen in order to free up the linebackers, disrupt the backfield (behind the offensive line) of the offense, and tackle the running back if he has the ball before he can gain yardage or the quarterback before he can throw or pass the ball. They are the first line of defense.
  • Behind the defensive line are the linebacker
    Linebacker
    A Linebacker is a position in American and Canadian football that was invented by football coach Fielding Yost of the University of Michigan. Linebackers are members of the defensive team, and line up approximately three to five yards behind the line of scrimmage, behind the defensive linemen...

    s
    . They line up between the defensive line and defensive backs and may either rush the quarterback or cover potential receivers.
  • The last line of defense is known as the secondary, comprising at least three players who line up as defensive back
    Defensive back
    In American football and Canadian football, defensive backs are the players on the defensive team who take positions somewhat back from the line of scrimmage; they are distinguished from the defensive line players and linebackers, who take positions directly behind or close to the line of...

    s
    , who are either cornerback
    Cornerback
    A cornerback is a member of the defensive backfield or secondary in American and Canadian football. Cornerbacks cover receivers, to defend against pass offenses and make tackles. Other members of the defensive backfield include the safeties and occasionally linebackers. The cornerback position...

    s
    or safeties
    Safety (American football)
    Safety is an American and Canadian football position played by a member of the defense. The safeties are defensive backs who line up from ten to fifteen yards behind the line of scrimmage. There are two variations of the position in a typical formation, the free safety and the strong safety ....

    . They cover the receivers and try to stop pass completions. They occasionally rush the quarterback.

Special teams


The units of players who handle kicking plays are known as special teams. Three important special-teams players are the punter, who handles punts, the placekicker
Placekicker
Placekicker, or simply kicker , is the title of the player in American and Canadian football who is responsible for the kicking duties of field goals, extra points, and, in many cases, kickoffs....

or kicker, who kicks off and attempts field goals and extra points, and the long snapper
Long snapper
In American football and Canadian football, the term long snapper refers to a player who is a specialized center during punts, field goals, and extra point attempts. His job is to snap the ball as quickly and accurately as possible....

, who snaps the ball for extra points, field goals, and punts. Also included on special teams are the returners. These players return punts or kickoffs and try to get in good field position. These players can also score touchdowns.

Uniform numbering



In the NFL, ranges of uniform numbers
Uniform number (American football)
In American football, uniform numbers are more unusual than in any other sport. They are displayed in more locations on the uniform than in those of other sports , and on the front of the jersey, they are displayed very large, taking up almost the entire front of the jersey...

 are (usually) reserved for certain positions:
  • 1–9: Quarterbacks, kickers, and punters
  • 10–19: Quarterbacks, kickers, punters, and wide receivers
  • 20–49: Running backs and defensive backs (tight ends are also permitted to wear numbers in the range 40-49 if no numbers are available in the range 80-89)
  • 50–59: Centers and linebackers
  • 60–79: Offensive and defensive linemen
  • 80–89: Wide receivers and tight ends
  • 90–99: Defensive linemen and linebackers


NCAA and high school rules specify only that offensive linemen must have numbers in the 50-79 range, but the NCAA "strongly recommends" that quarterbacks and running backs have numbers below 50 and wide receivers numbers above 79. This helps officials as it means that numbers 50 to 79 are ineligible receivers
Eligible receiver
In American football and Canadian football, not all players on offense are entitled to receive a forward pass. Only an eligible pass receiver may legally catch a forward pass, and only an eligible receiver may advance beyond the neutral zone if a forward pass which crosses the neutral zone is thrown...

, or players that may never receive a forward pass. There are no numbering restrictions on defensive players in the NCAA, other than that a team may not have two players on the field at the same time with the same jersey number
Squad number
In team sports, the squad number, shirt number, jersey number, sweater number, uniform number or simply a number is the number worn on a player's uniform, to identify and distinguish each player from others wearing the same or similar uniforms...

.

Basic strategy


Because the game stops after every down, giving teams a chance to call a new play, strategy plays a major role in football. Each team has a playbook of dozens to hundreds of plays. Ideally, each play is a scripted, strategically sound team-coordinated endeavor. Some plays are very safe; they are likely to get only a few yards. Other plays have the potential for long gains but at a greater risk of a loss of yardage or a turnover.

Generally speaking, rushing plays are less risky than passing plays. However, there are relatively safe passing plays and risky running plays. To deceive the other team, some passing plays are designed to resemble running plays and vice versa. These are referred to as play-action passes and draws, respectively. There are many trick or gadget plays, such as when a team lines up as if it intends to punt and then tries to run or pass for a first down. Such high-risk plays are a great thrill to the fans when they work. However, they can spell disaster if the opposing team realizes the deception and acts accordingly.

The defense also plans plays in response to expectations of what the offense will do. For example, a "blitz" (using linebackers or defensive backs to charge the quarterback) is often attempted when the team on defense expects a pass. A blitz makes downfield passing more difficult but exposes the defense to big gains if the offensive line stems the rush.

Many hours of preparation and strategizing, including film review by both players and coaches, go into the days between football games. This, along with the demanding physicality of football (see below), is why teams typically play at most one game per week.

Physicality



American football is a collision sport. To stop the offense from advancing the ball, the defense must tackle the player with the ball by knocking or pulling him down. As such, defensive players must use some form of physical contact to bring the ball-carrier to the ground, within certain rules and guidelines. Tacklers cannot kick or punch the runner. They also cannot grab the face mask of the runner's helmet or lead into a tackle with their own helmet. Despite these and other rules regarding unnecessary roughness, most other forms of tackling are legal. Blockers and defenders trying to evade them also have wide leeway in trying to force their opponents out of the way. Quarterbacks are regularly hit by defenders coming on full speed from outside the quarterback's field of vision. This is commonly known as a blindside.

To compensate for this, players must wear special protective equipment, such as a padded plastic helmet
Football helmet
A football helmet is a protective device used primarily in American football and Canadian football, the modern hard plastic version of which was created by Paul Brown. It consists of a hard plastic top with thick padding on the inside, a facemask made of one or more metal bars, and a chinstrap used...

, shoulder pads
Shoulder pads
Shoulder pads are a piece of protective equipment used in American and Canadian football. Most modern shoulder pads consist of a shock absorbing foam material with a hard plastic outer covering. The pieces are usually secured by rivets or strings that the user can tie to adjust the size.A related...

, hip pads and knee pad
Knee pad
Kneepads or knee pads are protective gear worn on knees to protect them against impact injury during , e.g., a fall or a strike, or to provide padding for extended kneeling.-In sports:...

s. These protective pads were introduced decades ago and have improved ever since to help minimize lasting injury
Injury
Injury or bodily injury is damage or harm caused to the structure or function of the body caused by an outside agent or force, which may be physical or chemical, and either by accident or intentional. Personal Injury also refers to damage caused to the reputation of another rather than physical...

 to players. An unintended consequence
Unintended consequence
Unintended consequences are outcomes that are not the results originally intended by a particular action. The unintended results may be foreseen or unforeseen, but they should be the logical or likely results of the action...

 of all the safety equipment has resulted in increasing levels of violence in the game. Players may now hurl themselves at one another at high speeds without a significant chance of injury. The injuries that do result tend to be severe and often season or career-ending and sometimes fatal. In previous years with less padding, tackling more closely resembled tackles in Rugby football
Rugby football
Rugby football may refer to a number of sports through history descended from a common form of football developed in different areas of the United Kingdom. Today it refers to either rugby league or rugby union.- History :...

. Better helmets have allowed players to use their helmets as weapons. This form of tackling is particularly unwise, because of the great potential for brain or spinal injury
Spinal cord injury
Spinal cord injuries cause myelopathy or damage to white matter or myelinated fiber tracts that carry signals to and from the brain. This type of traumatic injury could also damage the gray matter in the central part of the cord, causing segmental losses of interneurons and motorneurons...

. All this has caused the various leagues, especially the NFL, to implement a complicated series of penalties for various types of contact. Most recently, virtually any contact with the helmet of a defensive player on the quarterback, or any contact to the quarterback's head, is now a foul. During the late 1970s, the penalty in high school football for spearing included ejection from the game.

Despite protective equipment and rule changes to emphasize safety, injuries remain very common in football. It is increasingly rare, for example, for NFL quarterbacks or running backs (who take the most direct hits) to make it through an entire season without missing some time to injury. Additionally, 28 football players died from direct football injuries in the years 2000-05 and an additional 68 died indirectly from dehydration or other examples of "non-physical" dangers, according to the National Center for Catastrophic Sport Injury Research. Concussions are common, with about 41,000 suffered every year among high school players according to the Brain Injury Association of Arizona. In 1981, U.S. President Ronald Reagan
Ronald Reagan
Ronald Wilson Reagan was the 40th President of the United States and the 33rd Governor of California .Born in Tampico, Illinois, Reagan moved to Los Angeles, California in the 1930s...

, who played football in high school, commented on the contact of the sport: "[Football] is the last thing left in civilization where men can literally fling themselves bodily at one another in combat and not be at war."

Extra and optional equipment such as neck rolls, spider pads, rib protectors (referred to as "flak jackets"), and elbow pads
Elbow pad
thumb|left|200px|Rollerblader wearing elbow padsElbow pads are protective padded gear worn on the elbows to protect them against injury during a fall or a strike....

 help against injury as well, though they do not tend to be used by the majority of players due to their lack of requirement.

The danger of football and the equipment required to reduce it make regulation football impractical for casual play. Flag football
Flag football
Flag football is a version of American football that is popular worldwide. The basic rules of the game are similar to those of the mainstream game , but instead of tackling players to the ground, the defensive team must remove a flag or flag belt from the ball carrier to end a down...

 and touch football
Touch football (American)
Touch football is a version of American football usually played by amateurs on a recreational basis in which the players "tackle" the individual carrying the ball only by touching him with one or two hands, based on whether one is playing the one-hand touch or two-hand touch variety, as opposed to...

 are less violent variants of the game popular among recreational players.

Nutrition and dehydration


Football players typically begin their season while the weather is still extremely warm and with the dangerous combination of warm weather and high humidity, receiving dehydration is a great risk taken by the players. The players are usually required to follow a hydration schedule. It is extremely important for players to drink enough fluids because dehydration can seriously reduce athletic performance and increase the risk of heat illnesses. Most trainers and coaches make it imperative for their players to drink fluids before they are thirsty.

Brain injury


The Concussions Committee of the NFL, co-chaired by Dr. Ira Casson, has generally denied that concussions result in permanent brain injury. However, there is some research, reported in 2009, which, using phone interviews based on the National Health Interview Survey, showed increased incidence of diagnosis of memory loss
Memory loss
Memory loss can have many causes:*Alzheimer's disease is an illness which can cause mild to severe memory loss.*Parkinson's disease is a genetic defect which may result in memory loss....

 and dementia
Dementia
Dementia is a serious cognitive disorder. It may be static, the result of a unique global brain injury or progressive, resulting in long-term decline in cognitive function due to damage or disease in the body beyond what might be expected from normal aging...

 among retired professional football players. Such symptoms are believed related to the effects of concussion. More rigorous research is being conducted by Dr. Casson, neurologist, for the NFL. This finding is considered significant as such injuries may potentially affect high school and college players also.

Calendar


Traditionally, football is an autumn sport. A season typically begins in mid-to-late August and runs through December, into January. The professional playoffs run through January, and the Super Bowl
Super Bowl
The Super Bowl is the championship game of the National Football League, the premier association of professional American football. In most years, the Super Bowl is the most-watched American television broadcast. Many popular singers and musicians have performed during the event’s pre-game and...

 is often played in the first week of February.

The NFL draft
NFL Draft
The NFL Draft is an annual two-day event in which the 32 NFL teams select new players from the NCAA college system. It is the NFL's most common source of player recruitment.-Venue:...

 is usually held in April, in which eligible college football players are selected by NFL teams, the order of selection determined by the teams' final regular season records.

It is a long-standing tradition in the United States (though not universally observed) that high school football games are played on Friday night, college games on Saturday, and professional games on Sunday.

In the 1970s, the NFL began to schedule one game on Monday nights
Monday Night Football
Monday Night Football is a live television broadcast of the National Football League. Originally airing on the ABC network from to , Monday Night Football was the second longest running prime time show on American broadcast network television and one of the highest-rated, particularly among male...

. Beginning in 2006, the NFL began scheduling games on Thursday and Saturday nights after the college football regular season concludes in mid-November, aired on the NFL Network
NFL Network
NFL Network is an American television specialty channel dedicated to American football. It is owned and operated by the National Football League and is also shown in Canada and Mexico. It was launched November 4, 2003, only eight months after the league's 32 team owners voted unanimously to...

.

In recent years, nationally televised Thursday night college games have become a weekly fixture on ESPN
ESPN
ESPN is an American cable television network dedicated to broadcasting and producing sports-related programming 24 hours a day....

, and most nights of the week feature at least one college game, though most games are still played on the traditional Saturday.

Certain fall and winter holiday
Holiday
The words holiday or vacation have related meanings in different English-speaking countries and continents, but usually refer to one of the following activities or events:...

s—such as the NFL's Thanksgiving Classic
Thanksgiving Classic
The National Football League's Thanksgiving Classic is a series of games played during the Thanksgiving holiday in the United States. It has been a regular occurrence since the league's inception in 1920. Since 2006 three games are played every Thanksgiving. The first two are hosted by the Detroit...

 and numerous New Year's Day
New Year's Day
New Year's Day is the first day of the new year. On the modern Gregorian calendar, it is celebrated on January 1, as it was also in ancient Rome . In all countries using the Gregorian calendar as their main calendar, except for Israel, it is a public holiday, often celebrated with fireworks at the...

 college bowl games
Bowl game
In the United States, a bowl game is commonly considered to refer to one of a number of post-season college football games. Prior to 2002, bowl game statistics were not included in players' career totals and the games were mostly considered to be exhibition games involving a payout to participating...

—have traditional football games associated with them.

Despite this, there are a few professional leagues that have played in the spring, mainly to avoid competition with the established leagues. Examples include the now defunct XFL
XFL
The XFL was a professional American football league that played for one season in 2001. The league was founded by Vince McMahon, better known as the owner of the World Wrestling Entertainment...

, the United States Football League
United States Football League
The United States Football League was an American football league that played three seasons between 1983 and 1985. Although it lasted only three years and lost over $163 million, it was by far the National Football League's strongest competitor since the 1960s' American Football League...

, and the proposed All American Football League
All American Football League
The All American Football League is a proposed professional American football league. The league, which combines a professional pay structure with the requirement that all players be college graduates, had originally been scheduled to start in the spring of 2007, but later postponed its launch to...

. Indoor football
Indoor football
Indoor football is a variation of American football with rules modified to make it suitable for play within indoor arenas.-Early history:The first documented indoor football games were those played at Madison Square Garden in 1902 and 1903 known as the "World Series of Pro Football." They were the...

 is played primarily in spring for this same reason.

At most levels of competition, college football teams hold several weeks of practices in the spring. These practices typically end with an intramural scrimmage open to the public. In certain areas, high school football teams also hold spring practices.

Outside the United States


Outside the United States, the sport is referred to as "American football" (or a translation thereof) to differentiate it from other football
Football
Football is the name of several similar team sports, all of which involve kicking a ball with the foot in an attempt to score a goal. The most popular of these sports worldwide is association football, more commonly known as just "football" or "soccer"...

 codes such as association football (soccer), rugby football
Rugby football
Rugby football may refer to a number of sports through history descended from a common form of football developed in different areas of the United Kingdom. Today it refers to either rugby league or rugby union.- History :...

 and Australian rules football
Australian rules football
Australian football, also commonly referred to as Australian rules football, football, or Aussie rules, colloquially as footy, and historically as Australasian football or Victorian football, is a variant of football played between two teams of 18 players, plus four interchange players, outdoors on...

. In Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...

 and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous smaller islands, most notably Stewart Island/Rakiura and the Chatham Islands. The indigenous Māori named New Zealand Aotearoa, commonly translated as The Land of the Long White Cloud...

 the game is also known as gridiron football
Gridiron football
Gridiron football is an umbrella term used to refer to several similar codes of football played primarily in the United States and Canada. The term refers to the sport's characteristic field of play, which is marked with a series of parallel lines resembling a gridiron...

, or more commonly as gridiron, although in the United States the term gridiron refers only to the playing field itself. In much of the world, the term football
Football (word)
The English language word football may mean any one of several team sports , depending on the national or regional origin and location of the person using the word....

 is unambiguous and refers to association football.

The NFL has attempted to introduce the game to other nations and operated a developmental league, NFL Europa, with teams in five German cities and one in the Netherlands, but this league folded following the 2007 season. The professional Canadian Football League
Canadian Football League
The Canadian Football League or CFL is a professional sports league located entirely in Canada.Its eight teams, which are located in eight cities, are divided into two divisions of four teams each . The league's nineteen-week regular season runs from mid-June to early November. Each team plays...

 and collegiate Canadian Interuniversity Sport
Canadian Interuniversity Sport
Canadian Interuniversity Sport is the national governing body of university sport in Canada, comprising the majority of degree granting universities in the country. Its equivalent body for organized sports at colleges in Canada is The Canadian Colleges Athletic Association...

 play under the only slightly different Canadian rules
Canadian football
Canadian football is a form of gridiron football played almost exclusively in Canada in which two teams of 12 players each compete for territorial control of a field of play long and wide , attempting to advance a pointed prolate spheroid ball into the opposing team's scoring area...

.

In the UK, 46 teams play in the British American Football League
British American Football League
The British American Football League is the United Kingdom's primary American Football league. It was formerly known as the British Senior League until 2005....

. The BAFL has three levels: The Premier, of which there are five teams; BAFL 1, of which there are 19 teams; and BAFL 2, of which there are 26 teams. While the lower level teams have their own championship games during BritBowl Weekend, only Premier league teams face each other in the BritBowl
BritBowl
BritBowl is the Championship game of the British American Football League in the United Kingdom. It is the most prestigious of the league's three Bowl games that constitute BritBowl Weekend, an event held now annually at Keepmoat Stadium in Doncaster. Only teams in the Premier Division of BAFL are...

 which is it held in Doncaster
Doncaster
Doncaster is a large town in South Yorkshire, England, and the principal settlement of the Metropolitan Borough of Doncaster. The town is located about from Sheffield and is popularly referred to as "Donny"...

's Keepmoat Stadium. Unlike the NFL, the BAFL season is played through the summer (April to September), with the British university season
British Universities American Football League
The British Universities American Football League is an American football league contested by university teams in England, Wales and Scotland...

 spanning the autumn and winter.

In Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, the ONEFA
Mexican College Football
The National Student Organization of American Football, is a Mexican college football league....

 is a college league with 26 teams in 3 conferences.

In Japan
Japan
is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, the X-League
X-League
The X-League is a semi-professional American football league in Japan. It was founded in 1971 as the Japan American Football League. It changed its name to the X-league in 1997. There are four division between which there is promotion and relegation. Teams in the four-tier league are split into...

 is a professional league with 60 teams in four divisions, using promotion and relegation
Promotion and relegation
In many sports leagues around the world , promotion and relegation is a process that takes place at the end of each season in which teams are transferred between divisions...

. After the post-season playoffs, the X-League champion is determined in the Japan X Bowl. There are also over 200 universities fielding teams, with the national collegiate championship determined by the Koshien Bowl
Koshien Bowl
The Koshien Bowl is the annual Japanese American college football national championship game, usually played in December at Koshien Stadium.From the 2009 season until 2010 season, the game will be held as the final game of Japan University American Football Championship...

. The professional and collegiate champions then face each other in the Rice Bowl
Rice Bowl
The Rice Bowl is an annual American Football national championship game held in Japan every January 3rd that pits the Japanese college champion and the champion of the corporate X-League.- Champions :-External links:**X-League page, in Japanese*...

 to determine the national champion.

In Germany, the German Football League
German Football League
The German football League is the elite bundesliga for American football in Germany.- League set-up :The GFL is partitioned into north and south conferences, each with six teams. In each conference, every team plays against every other team of the own conference, both at home and away...

 whose elite division is called Bundesliga, has 12 teams partitioned into north and south conferences. The finalists from the playoffs determine the German champion during the German Bowl
German Football League
The German football League is the elite bundesliga for American football in Germany.- League set-up :The GFL is partitioned into north and south conferences, each with six teams. In each conference, every team plays against every other team of the own conference, both at home and away...

.

In Hungary, 18 registered teams participate in a the MAFL's two division league structure. The sport has grown significantly since 2004 and with some top Division I teams participating in the CEFL
Central European Football League
The Central European Football League is a regional American football league that includes clubs from Serbia, Slovenia, Hungary, Croatia, and Austria...

.

In Norway, div I consists of only two teams, Oslo Vikings
Oslo Vikings
Oslo Vikings is the name of an American football club located in Oslo, Norway, that competes in the Norway American Football Federation and the European Federation of American Football tournaments. The club was founded in 1986 and prior to 1992, the team was known as the Westside Vikings...

 and Eidsvoll 1814's. These two teams also compete in the European Football League
European Football League
The European Football League is a European Cup style tournament for European American Football teams affiliated to EFAF...

 but they play an annual game for the Norwegian Championship title. Norway has seven other teams that play in div II and this division is looked upon as the Norwegian Football League.

The International Federation of American Football
International Federation of American Football
International Federation of American Football is the international governing body of American football associations. Its headquarters are in La Courneuve, France, and its current president is Tommy Wiking...

 is the governing body for American football with 45 member associations from North and South America, Europe, Asia and Oceania. The IFAF also oversees the American Football World Cup, which is held every four years. Japan won the first two World Cups, held in 1999 and 2003. Team USA, which had not participated in the previous World Cups, won the title in 2007.

Major American leagues have also held some regular season games outside of the United States. On October 2, 2005, the Arizona Cardinals
Arizona Cardinals
The Arizona Cardinals are a professional American Football team based in Glendale, Arizona. The Cardinals are members of the Western Division of the National Football Conference in the National Football League . The Cardinals were founded in 1898, and are the oldest continuously run professional...

 and San Francisco 49ers
San Francisco 49ers
The San Francisco 49ers are a professional American football team. The team plays its home games in San Francisco, California, while the club's headquarters and practice facility are located in Santa Clara...

 played the first regular season NFL game outside of the United States, in Mexico City's Estadio Azteca
Estadio Azteca
Estadio Azteca is a stadium in Mexico City, Mexico. It is the official home stadium of the Mexico national football team and the Mexican team Club América....

, From 2007, the NFL has played or has plans to play at least one regular season game outside of the United States. The NCAA
National Collegiate Athletic Association
The National Collegiate Athletic Association is a voluntary association of about 1,281 institutions, conferences, organizations and individuals that organizes the athletic programs of many colleges and universities in the United States and Canada...

 will also play games outside of the U.S. In 2012, The United States Naval Academy will play the University of Notre Dame in Dublin, Ireland
Dublin
Dublin is the largest city and capital of Ireland. It is officially known in Irish as Baile Átha Cliath or Áth Cliath ; the English name comes from the Irish Dubh Linn meaning "black pool". It is located near the midpoint of Ireland's east coast, at the mouth of the River Liffey and at the...

.

See also


  • American football in the Netherlands
    American Football in the Netherlands
    - The Beginning :Dutch American Football has been on the map both nationally and internationally for more than twenty years. However, it took almost 40 years before the first American Football game played in the Netherlands was followed up. In 1946 two American University teams played an exhibition...

  • American football on Thanksgiving
  • American football positions
    American football positions
    In American football, each team has eleven players on the field at one time. Because the rules allow unlimited substitution between plays, however, the types of players on the field for each team differ depending on the situation...

  • College football
    College football
    College football is American football played by teams of student athletes fielded by American universities, colleges, and military academies. It was the venue through which American football first gained popularity in the United States...

  • Comparison of American football and rugby league
    Comparison of American football and rugby league
    A comparison of American football and rugby league football can be made because of their shared origins, resulting in similarities and shared concepts in terms of scoring and advancing the ball. Of all the world's sports , rugby league is the sport most similar to American football...

  • Eight-man football
    Eight-man football
    Eight-man football is a type of American football, generally played by small high schools. Rules and formations vary greatly among states and even among different organizations, but the one constant is eight players from each team on the field at one time, as opposed to eleven-man football, which...

  • Fantasy football (American)
    Fantasy football (American)
    Fantasy football is a fantasy sports game in which participants are arranged into a league. The person who creates the league is called the commissioner, and that person invites other owners into his/her league...

  • Glossary of American football
    Glossary of American football
    The following terms are used in American football and Canadian football, but see also the glossary of Canadian football.-0-9:3-3-5 defense:A variation of the Nickel formation with 3 linemen , 3 linebackers , and 5 defensive backs...

  • Gridiron football
    Gridiron football
    Gridiron football is an umbrella term used to refer to several similar codes of football played primarily in the United States and Canada. The term refers to the sport's characteristic field of play, which is marked with a series of parallel lines resembling a gridiron...

  • List of American football players
  • List of American Football League players
  • List of American football stadiums by capacity
  • List of American football teams in Germany
  • List of American football teams in the Netherlands
  • List of American football teams in the United Kingdom

  • List of defunct sports leagues
  • List of leagues of American and Canadian football
  • Nine-man football
    Nine-man football
    Nine-man football is a type of American football played by high schools that are too small to play the usual eleven-man game. As of 2007, Minnesota, North Dakota and South Dakota had nine man football....

  • American Football League
    American Football League
    The American Football League was a major Professional Football league that operated from 1960 until 1969, when it merged with the established National Football League . The upstart AFL operated in direct competition with the more established NFL throughout its existence...

  • National Football League
    National Football League
    The National Football League is the largest professional American football league in the world. It was formed by eleven teams in 1920 as the American Professional Football Association, with the league changing its name to the National Football League in 1922. The league currently consists of...

  • United Football League
  • All-America Football Conference
    All-America Football Conference
    The All-America Football Conference was a professional American football league that challenged the established National Football League from 1946 to 1949. One of the NFL’s most formidable challengers, the AAFC attracted many of the nation’s best players, produced one of pro football’s greatest...

  • World Football League
    World Football League
    The World Football League was a short-lived American football league that played in 1974 and part of 1975. Although this pro grid circuit's proclaimed ambition was to bring American football onto a worldwide stage, the farthest the WFL reached was placing a team – the Hawaiians – in Honolulu,...

  • United States Football League
    United States Football League
    The United States Football League was an American football league that played three seasons between 1983 and 1985. Although it lasted only three years and lost over $163 million, it was by far the National Football League's strongest competitor since the 1960s' American Football League...

  • Pro Football Hall of Fame
    Pro Football Hall of Fame
    The Pro Football Hall of Fame is the hall of fame of the National Football League . It opened in Canton, Ohio, United States, on September 7 1963 with 17 charter inductees...

  • Six-man football
    Six-man football
    Six-man football is a variant of high school American football that is played with six players per team, instead of 11.-History:Six-man football was developed in 1934 by Chester High School coach Stephen Epler as an alternative means for small high schools to field a football team during the Great...

  • Sprint Football
    Sprint football
    Sprint football is a varsity sport played by United States colleges and universities, under rules similar to American football. The sport is currently governed by the Collegiate Sprint Football League....

  • Steroid use in American football
    Steroid use in American football
    The use of performance enhancing drugs in the sport of American football has been an ongoing issue since the late 1980s, especially in the National Football League . The NFL began to test players for steroid use during the 1987 season, and started to issue suspensions to players during the 1989...

  • Strat-O-Matic Football
    Strat-O-Matic Football
    Strat-O-Matic Pro Football is a tabletop board game that was first produced by the Strat-O-Matic game company in 1968 and is issued with updated player cards and occasionally rules each year. Each year's new version is typically released in mid-August....

  • Street football (American)
    Street football (American)
    Street football, also known as backyard football, is a simplified variant of American football primarily played informally by youth. It features far less equipment and fewer rules than its counterparts, but unlike the similar touch football, features full tackling.-Main game:An organized version...

  • Sports nutrition
    Sports nutrition
    Sports nutrition is the study and practice of nutrition and diet as it relates to athletic performance. Although an important part of many sports training regimens, it is most commonly considered in strength sports and endurance sports...

  • XFL
    XFL
    The XFL was a professional American football league that played for one season in 2001. The league was founded by Vince McMahon, better known as the owner of the World Wrestling Entertainment...



Further reading

  • Sports Illustrated
    Sports Illustrated
    Sports Illustrated is an American sports magazine owned by media conglomerate Time Warner. It has over 3 million subscribers and is read by 23 million adults each week, including over 18 million men, 19% of the adult males in the United States. It was the first magazine with circulation over one...

    magazine dated December 4, 2005; "Football America", a series of articles attesting to the pervasive popularity of American football in the United States at all levels.

External links