American football, referred to as football in the United States and
Canada and also known as gridiron,[nb 1] is a team
sport played by two teams of eleven players on a rectangular field
with goalposts at each end. The offense, which is the team controlling
the oval-shaped football, attempts to advance down the field by
running with or passing the ball, while the defense, which is the team
without control of the ball, aims to stop the offense's advance and
aims to take control of the ball for themselves. The offense must
advance at least ten yards in four downs, or plays, and otherwise they
turn over the football to the defense; if the offense succeeds in
advancing ten yards or more, they are given a new set of four downs.
Points are primarily scored by advancing the ball into the opposing
team's end zone for a touchdown or kicking the ball through the
opponent's goalposts for a field goal. The team with the most points
at the end of a game wins.
American football evolved in the United States, originating from the
sports of association football and rugby football. The first match of
American football was played on November 6, 1869, between two college
teams, Rutgers and Princeton, under rules based on the association
football rules of the time. During the latter half of the 1870s,
colleges playing association football switched to the Rugby Union
code, which allowed carrying the ball. A set of rule changes drawn up
from 1880 onward by Walter Camp, the "Father of American Football",
established the snap, eleven-player teams, and the concept of downs;
later rule changes legalized the forward pass, created the neutral
zone, and specified the size and shape of the football.
American football as a whole is the most popular sport in the United
States. The most popular forms of the game are professional and
college football, with the other major levels being high school and
youth football. As of 2012[update], nearly 1.1 million high
school athletes and 70,000 college athletes play the sport in the
United States annually, almost all of them men, with a few exceptions.
Football League, the most popular American football
league, has the highest average attendance of any professional sports
league in the world; its championship game, the Super Bowl, ranks
among the most-watched club sporting events in the world, and the
league has an annual revenue of around US$10 billion.
1 Etymology and names
2.1 Early history
2.2 Evolution of the game
2.3 Professional era
3 Teams and positions
3.1 Offensive unit
3.2 Defensive unit
Special teams unit
4.2 Field and equipment
4.3 Duration and time stoppages
4.4 Advancing the ball and downs
4.6 Officials and fouls
6 Leagues and tournaments
6.1 Rival professional leagues
6.2 International play
7 Popularity and cultural impact
7.1 United States
7.2 Other countries
8 Variations and related sports
9 See also
13 Further reading
14 External links
Etymology and names
In the United States, American
Football is called "football." The
terms "gridiron" or "American football" are favored in
English-speaking countries where other codes of football are popular,
such as the United Kingdom, Ireland, New Zealand, and Australia.
Main article: History of American football
Part of the
American football series on
History of American football
• Origins of American football
• Early history of American football
• First game
• Walter Camp
• First pro player
• First pro league
• Modern history of American football
• Close relations:
• Medieval football
• Old division football
• Rugby football
• Association football
• Canadian football
• Black players in professional American football
• Homosexuality in American football
Concussions in American football
Rugby union comparison
Rugby league comparison
Canadian football comparison
Football Hall of Fame
Football Hall of Fame
• Years in American football
• NFL season-by-season
College football season-by-season
• Glossary of American football
American football Portal
American football evolved from the sports of association football
(soccer) and rugby football. Rugby football, like American football,
is a sport where two competing teams vie for control of a ball, which
can be kicked through a set of goalposts or run into the opponent's
goal area to score points.
What is considered to be the first
American football game was played
on November 6, 1869 between Rutgers and Princeton, two college teams.
The game was played between two teams of 25 players each and used a
round ball that could not be picked up or carried. It could, however,
be kicked or batted with the feet, hands, head or sides, with the
ultimate goal being to advance it into the opponent's goal. Rutgers
won the game 6 goals to 4. Collegiate play continued for
several years in which matches were played using the rules of the host
school. Representatives of Yale, Columbia, Princeton and Rutgers met
on October 19, 1873 to create a standard set of rules for all schools
to adhere to. Teams were set at 20 players each, and fields of 400 by
250 feet (122 m × 76 m) were specified. Harvard
abstained from the conference, as they favored a rugby-style game that
allowed running with the ball.
An 1875 Harvard-
Yale game played under rugby-style rules was observed
by two impressed Princeton athletes. These players introduced the
sport to Princeton, a feat the Professional
Association compared to "selling refrigerators to Eskimos."
Yale and Columbia then agreed to intercollegiate
play using a form of rugby union rules with a modified scoring
system. These schools formed the Intercollegiate Football
Yale did not join until 1879.
Yale player Walter
Camp, now regarded as the "Father of American Football",
secured rule changes in 1880 that reduced the size of each team from
15 to 11 players and instituted the snap to replace the chaotic and
Evolution of the game
A photograph of Walter Camp, the "Father of American Football", taken
in 1878 when Camp was captain of Yale's football team
The introduction of the snap resulted in unexpected consequences.
Prior to the snap, the strategy had been to punt if a scrum resulted
in bad field position. However, a group of Princeton players realized
that, as the snap was uncontested, they now could hold the ball
indefinitely to prevent their opponent from scoring. In 1881, both
teams in a game between Yale-Princeton used this strategy to maintain
their undefeated records. Each team held the ball, gaining no ground,
for an entire half, resulting in a 0–0 tie. This "block game" proved
extremely unpopular with the spectators and fans of both teams.
A rule change was necessary to prevent this strategy from taking hold,
and a reversion to the scrum was considered. However, Camp
successfully proposed a rule in 1882 that limited each team to three
downs, or tackles, to advance the ball five yards. Failure to advance
the ball the required distance within those three downs would result
in control of the ball being forfeited to the other team. This change
American football a separate sport from rugby, and
the resulting five-yard lines added to the field to measure distances
made it resemble a gridiron in appearance. Other major rule changes
included a reduction of the field size to 110 by 53.333 yards
(100.584 m × 48.768 m), and the adoption of a scoring
system that awarded four points for a touchdown, two for a safety and
a goal following a touchdown, and five for a goal from field;
additionally, tackling below the waist was legalized. The last,
and arguably most important innovation, which would at last make
American football uniquely "American", was the legalization of
interference, or blocking, a tactic which was highly illegal under the
Despite these new rules, football remained a violent sport. Dangerous
mass-formations, which involved interlocking interference, like the
flying wedge resulted in serious injuries and deaths. A 1905 peak
of 19 fatalities nationwide resulted in a threat by President Theodore
Roosevelt to abolish the game unless major changes were made. In
response, sixty-two colleges and universities met in New York City to
discuss rule changes on December 28, 1905, and these proceedings
resulted in the formation of the Intercollegiate Athletic Association
of the United States, later named the National Collegiate Athletic
The legal forward pass was introduced in 1906, although its impact was
initially limited due to the restrictions placed on its use. Other
rule changes introduced that year included the reduction of the time
of play from 70 to 60 minutes and the increase of the distance
required for a first down from 5 to 10 yards (9.1 m). To reduce
infighting and dirty play between teams, the neutral zone was created
along the width of the football. Scoring was also adjusted: field
goals were lowered to three points in 1909 and touchdowns were
raised to six points in 1912. The field was also reduced to 100
yards (91 m) long, but two 10-yard-long end zones were created,
and teams were given four downs instead of three to advance the ball
10 yards (9.1 m). The roughing-the-passer penalty was
implemented in 1914, and eligible players were first allowed to catch
the ball anywhere on the field in 1918.
William "Pudge" Heffelfinger, widely regarded as the first
professional football player
On November 12, 1892, William "Pudge" Heffelfinger was paid $500 to
play a game for the
Allegheny Athletic Association
Allegheny Athletic Association in a match against
the Pittsburgh Athletic Club. This is the first recorded instance of a
player being paid to participate in a game of American football,
although many athletic clubs in the 1880s offered indirect benefits,
such as helping players attain employment, giving out trophies or
watches that players could pawn for money, or paying double in expense
money. Despite these extra benefits, the game had a strict sense of
amateurism at the time, and direct payment to players was frowned
upon, if not outright prohibited.
Over time, professional play became increasingly common, and with it
came rising salaries and unpredictable player movement, as well as the
illegal payment of college players who were still in school. The
National Football League
National Football League (NFL), a group of professional teams that was
originally established in 1920 as the American Professional Football
Association, aimed to solve these problems. This new league's stated
goals included an end to bidding wars over players, prevention of the
use of college players, and abolition of the practice of paying
players to leave another team. By 1922, the NFL had established
itself as the premier professional football league.
The dominant form of football at the time was played at the collegiate
level, but the upstart NFL received a boost to its legitimacy in 1925
when an NFL team, the Pottsville Maroons, defeated a team of Notre
Dame all-stars in an exhibition game. A greater emphasis on the
passing game helped professional football to further distinguish
itself from the college game during the late 1930s.
general became increasingly popular following the 1958 NFL
Championship game, a match between the
Baltimore Colts and the New
York Giants that is still referred to as the "Greatest Game Ever
Played". The game, a 23–17 overtime victory by the Colts, was seen
by millions of television viewers and had a major impact on the
popularity of the sport. This, along with the innovations introduced
by the new
American Football League
American Football League (AFL) in the early 1960s, helped
football to become the most popular sport in the United States by the
American Football League
American Football League arose in 1960 and challenged the
NFL's dominance. The AFL began in relative obscurity but eventually
thrived, with an initial television contract with the ABC network. The
AFL's existence forced the conservative NFL to expand to Dallas and
Minnesota in an attempt to destroy the new league. Meanwhile, the AFL
introduced many new features to Professional
Football in the United
States: official time on the scoreboard clock, rather than on a watch
in the referee's pocket, as the NFL did; optional two-point
conversions by pass or run after touchdowns; names on the jerseys of
players; and several others, including expansion of the role of
minority players, actively recruited by the league in contrast to the
NFL. The AFL also signed several star college players that had also
been drafted by NFL teams. Competition for players heated up in 1965,
when the AFL
New York Jets
New York Jets signed rookie
Joe Namath to a then-record
US$437,000 contract. A five-year, $40 million
contract followed, which helped to sustain the young league. The
bidding war for players ended in 1966, when NFL owners approached the
AFL regarding a merger, and the two leagues agreed on one that would
take full effect in 1970. This agreement provided for a common draft
that would take place each year, and it instituted an annual World
Championship game to be played between the champions of each league.
That game began play at the end of the 1966 season. Once the merger
was completed, it was no longer a championship game between two
leagues, and reverted to the NFL championship game, which came to be
known as the Super Bowl.
College football maintained a tradition of postseason bowl games. Each
bowl game would be associated with a particular conference, and
earning a spot in a bowl game was the reward for winning a conference.
This arrangement was profitable, but it tended to prevent the two
top-ranked teams from meeting in a true national championship game, as
they would normally be committed to the bowl games of their respective
conferences. Several systems have been used since 1992 to determine a
national champion of college football. The first was the Bowl
Coalition, in place from 1992 to 1994. This was replaced in 1995 by
the Bowl Alliance, which gave way in 1997 to the Bowl Championship
Series (BCS). The BCS arrangement proved to be controversial, and
was replaced in 2014 by the
College Football Playoff
College Football Playoff (CFP).
Teams and positions
American football positions
A football game is played between two teams of 11 players
each. Playing with more on the field is punishable by a
penalty. Teams may substitute any number of their players
between downs; this "platoon" system replaced the original
system, which featured limited substitution rules, and has resulted in
teams utilizing specialized offensive, defensive and special teams
Individual players in a football game must be designated with a
uniform number between 1 and 99. NFL teams are required to number
their players by a league-approved numbering system, and any
exceptions must be approved by the Commissioner. NCAA and NFHS
teams are "strongly advised" to number their offensive players
according to a league-suggested numbering scheme.
The role of the offensive unit is to advance the football down the
field with the ultimate goal of scoring a touchdown.
A diagram of a typical pre-snap formation. The offense (red) is lined
up in a variation of the I formation, while the defense (blue) is
lined up in the 4–3 defense. Both formations are legal.
The offensive team must line up in a legal formation before they can
snap the ball. An offensive formation is considered illegal if there
are more than four players in the backfield or fewer than five players
numbered 50–79 on the offensive line. Players can
temporarily line up in a position whose eligibility is different from
what their number permits as long as they immediately report the
change to the referee, who then informs the defensive team of the
change. Neither team's players, with the exception of the snapper,
are allowed to line up in or cross the neutral zone until the ball is
snapped. Interior offensive linemen are not allowed to move until the
snap of the ball.
A quarterback for the
Kiel Baltic Hurricanes
Kiel Baltic Hurricanes under center, ready to
take the snap
The main backfield positions are the quarterback (QB),
halfback/tailback (HB/TB) and fullback (FB). The quarterback is the
leader of the offense. Either he or a coach calls the plays.
Quarterbacks typically inform the rest of the offense of the play in
the huddle before the team lines up. The quarterback lines up behind
the center to take the snap and then hands the ball off, throws it or
runs with it.
The primary role of the halfback, also known as the tailback, is to
carry the ball on running plays. Halfbacks may also serve as
receivers. Fullbacks tend to be larger than halfbacks and function
primarily as blockers, but they are sometimes used as runners in
short-yardage situations and are seldom used in passing
The offensive line (OL) consists of several players whose primary
function is to block members of the defensive line from tackling the
ball carrier on running plays or sacking the quarterback on passing
plays. The leader of the offensive line is the center (C), who is
responsible for snapping the ball to the quarterback, blocking,
and for making sure that the other linemen do their jobs during the
play. On either side of the center are the guards (G), while
tackles (T) line up outside the guards.
Washington Redskins wide receiver
Santana Moss catches a pass over two
Atlanta Falcons defenders.
The principal receivers are the wide receivers (WR) and the tight ends
(TE). Wide receivers line up on or near the line of scrimmage,
split outside the line. The main goal of the wide receiver is to catch
passes thrown by the quarterback, but they may also function as
decoys or as blockers during running plays. Tight ends line up outside
the tackles and function both as receivers and as blockers.
Dallas Cowboys defensive players force
Houston Texans running back
Arian Foster to fumble the ball.
The role of the defense is to prevent the offense from scoring by
tackling the ball carrier or by forcing turnovers (interceptions or
The defensive line (DL) consists of defensive ends (DE) and defensive
tackles (DT). Defensive ends line up on the ends of the line, while
defensive tackles line up inside, between the defensive ends. The
primary responsibilities of defensive ends and defensive tackles is to
stop running plays on the outside and inside, respectively, to
pressure the quarterback on passing plays, and to occupy the line so
that the linebackers can break through.
Linebackers line up behind the defensive line but in front of the
defensive backfield. They are divided into two types: middle
linebackers (MLB) and outside linebackers (OLB). Linebackers are the
defensive leaders and call the defensive plays. Their diverse roles
include defending the run, pressuring the quarterback, and guarding
backs, wide receivers and tight ends in the passing game.
Brent Grimes of the
Hamburg Sea Devils
Hamburg Sea Devils intercepts a pass.
The defensive backfield, often called the secondary, consists of
cornerbacks (CB) and safeties (S). Safeties are themselves divided
into free safeties (FS) and strong safeties (SS). Cornerbacks line
up outside the defensive formation, typically opposite of a receiver
so as to be able to cover him, while safeties line up between the
cornerbacks but farther back in the secondary. Safeties are the last
line of defense, and are responsible for stopping deep passing plays
as well as running plays.
Special teams unit
The special teams unit is responsible for all kicking plays. The
special teams unit of the team in control of the ball will try and
execute field goal (FG) attempts, punts and kickoffs, while the
opposing team's unit will aim to block or return them.
Kicker Jeff Reed of the
Pittsburgh Steelers executes a kickoff.
Three positions are specific to the field goal and PAT
(point-after-touchdown) unit: the placekicker (K or PK), holder (H)
and long snapper (LS). The long snapper's job is to snap the football
to the holder, who will catch and position it for the placekicker.
There is not usually a holder on kickoffs, because the ball is kicked
off of a tee; however, a holder may be used in certain situations,
such as if wind is preventing the ball from remaining upright on the
tee. The player on the receiving team who catches the ball is known as
the kickoff returner (KR).
The positions specific to punt plays are the punter (P), long snapper,
and gunner. The long snapper snaps the football directly to the
punter, who then drops and kicks it before it hits the ground. Gunners
line up split outside the line and race down the field, aiming to
tackle the punt returner (PR) – the player that catches the
American football rules
A player (dark jersey) scores a touchdown while a defender (in white)
looks on. The goal line is marked by the small orange pylon.
In American football, the winner is the team that has scored the most
points at the end of the game. There are multiple ways to score in a
The touchdown (TD), worth six points, is the most valuable scoring
play in American football. A touchdown is scored when a live ball is
advanced into, caught in, or recovered in the end zone of the opposing
team. The scoring team then attempts a try or conversion, more
commonly known as the point(s)-after-touchdown (PAT), which is a
single scoring opportunity.
A PAT is most commonly attempted from the two- or three-yard line,
depending on the level of play. If scored by a placekick or dropkick
through the goal posts, it is worth one point, and is typically called
the extra point. Conversely, a team may elect to run a single play
from scrimmage and attempt, once again, to achieve what would normally
be considered a touchdown. In such a case, a successful attempt is
called the two-point conversion and is worth two points. For the
2015 season, the NFL adopted a rules on PATs that stated during an
extra point the placekick must be hiked from the 15-yard line and on
extra points if the kick is blocked and the opposing team returns it
into the end zone or if during a two-point conversion the ball is
fumbled or intercepted and returned to the end zone the opposing team
will score two points. No points are awarded on a failed extra point
or two-point conversion attempt. In general, the extra
point is almost always successful in professional play and is only
slightly less successful at amateur levels, while the two-point
conversion is a much riskier play with a higher probability of
failure; accordingly, extra point attempts are far more common than
two-point conversion attempts.
A field goal (FG), worth three points, is scored when the ball is
placekicked or dropkicked through the uprights and over the crossbars
of the defense's goalposts. After a PAT attempt or
successful field goal the scoring team must kick the ball off to the
A safety is scored when the ball carrier is tackled in his own end
zone. Safeties are worth two points, which are awarded to the
defense. In addition, the team that conceded the safety must kick
the ball to the scoring team via a free kick.
Field and equipment
A football field as seen from behind one end zone. The tall, yellow
goal posts mark where the ball must pass for a successful field goal
or extra point. The large, rectangular area marked with the team name
is the end zone.
Football games are played on a rectangular field that measures 120
yards (110 m) long and 53.33 yards (48.76 m) wide. Lines
marked along the ends and sides of the field are known respectively as
the end lines and sidelines, and goal lines are marked 10 yards
(9.1 m) inward from each end line. Weighted pylons are placed on
the inside corner of the intersections of the goal lines and end
White markings on the field identify the distance from the end zone.
Inbound lines, or hash marks, are short parallel lines that mark off 1
yard (0.91 m) increments. Yard lines, which can run the width of
the field, are marked every 5 yards (4.6 m). A one yard wide is
placed at each end of the field; this line is marked at the center of
the two-yard line in professional play and at the three-yard line in
college play. Numerals that display the distance from the closest goal
line in yards are placed on both sides of the field every ten
Goalposts are located at the center of the plane of each of the two
end lines. The crossbar of these posts is ten feet (3.0 meters) above
the ground, with vertical uprights at the end of the crossbar
18 feet 6 inches (5.64 m) apart for professional and
collegiate play and 23 feet 4 inches (7.11 m) apart for
high school play. The uprights extend vertically 35 feet
on professional fields, a minimum of 10 yards on college fields, and a
minimum of ten feet on high school fields. Goal posts are padded at
the base, and orange ribbons are normally placed at the tip of each
The football itself is an oval ball, similar to the balls used in
rugby or Australian rules football. At all levels of play, the
football is inflated to 12 1⁄2 to 13 1⁄2 pounds
per square inch (psi) and weighs 14 to 15 ounces (397 to 425
grams); beyond that, the exact dimensions vary slightly.
In professional play the ball has a long axis of 11 to
11 1⁄4 inches, a long circumference of 28 to
28 1⁄2 inches, and a short circumference of 21 to
21 1⁄4 inches, while in college and high school play the
ball has a long axis of 10 7⁄8 to 11 7⁄16 inches,
a long circumference of 27 3⁄4 to 28 1⁄2 inches,
and a short circumference of 20 3⁄4 to 21 1⁄4
Duration and time stoppages
Football games last for a total of 60 minutes in professional and
college play and are divided into two-halves of 30 minutes and
four-quarters of 15 minutes.
High school football
High school football games are 48
minutes in length with two-halves of 24 minutes and four-quarters of
12 minutes. The two-halves are separated by a halftime period, and
the first and third quarters are also followed by a short
break. Prior to the start of the game, the referee and
team captains for each team meet at midfield for a coin toss. The
visiting team is allowed to call 'heads' or 'tails'; the winner of the
toss is allowed to decide between choosing whether to receive or kick
off the ball or choosing which goal they want to defend, but they can
also defer their choice until the second half. The losing team, unless
the winning team decides to defer, is allowed to choose the option the
winning team did not select, and receives the option to receive, kick,
or select a goal to defend to begin the second half. Most teams choose
to receive or defer, because choosing to kick the ball to start the
game would allow the other team to choose which goal to defend.
Teams switch goals following the first and third quarters. If a
down is in progress when a quarter ends, play continues until the down
Games last longer than their defined length due to play stoppages –
the average NFL game lasts slightly over three hours. Time in a
football game is measured by the game clock. An operator is
responsible for starting, stopping and operating the game clock based
on the direction of the appropriate official. A separate
clock, the play clock, is used to determine if a delay of game
infraction has been committed. If the play clock expires before the
ball has been snapped or free-kicked, a delay of game foul is called
on the offense. The play clock is set to 40 seconds in professional
and college football and to 25 seconds in high school play or
following certain administrative stoppages in the former levels of
Advancing the ball and downs
Carolina Panthers quarterback
Jake Delhomme (number 17) in the motion
of throwing a forward pass.
There are two main ways that the offense can advance the ball: running
and passing. In a typical play, the quarterback calls the play, and
the center passes the ball backwards and under his legs to the
quarterback in a process known as the snap. The quarterback then
either hands the ball off to a back, throws the ball or runs with it
himself. The play ends when the player with the ball is tackled or
goes out of bounds, or a pass hits the ground without a player having
caught it. A forward pass can only be legally attempted if the passer
is behind the line of scrimmage. In the NFL, a down also ends if
the runner's helmet comes off.
The offense is given a series of four plays, known as downs. If the
offense advances ten or more yards in the four downs, they are awarded
a new set of four downs. If they fail to advance ten yards, possession
of the football is turned over to the defense. In most situations, if
the offense reaches their fourth down they will punt the ball to the
other team, which forces them to begin their drive from further down
the field; if they are in field goal range, they might also attempt to
score a field goal. A group of officials, the chain crew, keeps
track of both the downs and the distance measurements. On
television, a yellow line is electronically superimposed on the field
to show the first down line to the viewing audience.
Green Bay Packers
Green Bay Packers placekicker
Mason Crosby attempts a field goal by
kicking the ball from the hands of a holder. This is the standard
method to score field goals or extra points.
There are two categories of kicks in football: scrimmage kicks, which
can be executed by the offensive team on any down from behind or on
the line of scrimmage, and free kicks. The
free kicks are the kickoff, which starts the first and third quarters
and overtime and follows a try attempt or a successful field goal, and
the safety kick, which follows a safety.
On a kickoff, the ball is placed at the 35-yard line of the kicking
team in professional and college play and at the 40-yard line in high
school play. The ball may be drop-kicked or place-kicked. If a place
kick is chosen, the ball can be placed on the ground or on a tee, and
a holder may be used in either case. On a safety kick, the kicking
team kicks the ball from their own 20-yard line. They can punt,
drop-kick or place-kick the ball, but a tee may not be used in
professional play. Any member of the receiving team may catch or
advance the ball, and the ball may be recovered by the kicking team
once it has gone at least ten yards and has touched the ground or has
been touched by any member of the receiving team.
The three types of scrimmage kicks are place kicks, drop kicks, and
punts. Only place kicks and drop kicks can score points.
The place kick is the standard method used to score points,
because the pointy shape of the football makes it difficult to
reliably drop kick. Once the ball has been kicked from a
scrimmage kick, it can be advanced by the kicking team only if it is
caught or recovered behind the line of scrimmage. If it is touched or
recovered by the kicking team beyond this line, it becomes dead at the
spot where it was touched. The kicking team is
prohibited from interfering with the receiver's opportunity to catch
the ball, and the receiving team has the option of signaling for a
fair catch. This prohibits the defense from blocking into or tackling
the receiver, but the play ends as soon as the ball is caught and the
ball may not be advanced.
Officials and fouls
See also: Official (American football), Chain crew, and Penalty
Officials discuss a call on the field.
Officials use the chains to measure for a first down. Here, the ball
is just short of the pole and therefore short of a first down.
Officials are responsible for enforcing game rules and monitoring the
clock. All officials carry a whistle and wear black-and-white striped
shirts and black hats except for the referee, whose hat is white. Each
carries a weighted yellow flag that is thrown to the ground to signal
that a foul has been called. An official who spots multiple fouls will
throw his hat as a secondary signal. The seven officials on the
field are each tasked with a different set of responsibilities:
The referee is positioned behind and to the side of the offensive
backs. He is charged with oversight and control of the game and is the
authority on the score, the down number, and any and all rule
interpretations in discussions between the other officials. He
announces all penalties and discusses the infraction with the
offending team's captain, monitors for illegal hits against the
quarterback, makes requests for first-down measurements, and notifies
the head coach whenever a player is ejected. He positions himself to
the passing arm side of the quarterback. In most games, the referee is
responsible for spotting the football prior to a play from scrimmage.
The umpire is positioned in the defensive backfield, except in the
NFL, where he is positioned lateral to the referee on the opposite
side of the formation. He watches play along the line of scrimmage to
make sure that no more than 11 offensive players are on the field
prior to the snap and that no offensive linemen are illegally
downfield on pass plays. He monitors the contact between offensive and
defensive linemen and calls most of the holding penalties. The umpire
records the number of timeouts taken and the winner of the coin toss
and the game score, assists the referee in situations involving
possession of the ball close to the line of scrimmage, determines
whether player equipment is legal, and dries wet balls prior to the
snap if a game is played in rain.
The back judge is positioned deep in the defensive backfield, behind
the umpire. He ensures that the defensive team has no more than 11
players on the field and determines whether catches are legal, whether
field goal or extra point attempts are good, and whether a pass
interference violation occurred. The back judge is also responsible
for the play clock, the time between each play, when a visible play
clock is not used.
The head linesman is positioned on one end of the line of scrimmage.
He watches for any line-of-scrimmage and illegal use-of-hands
violations and assists the line judge with illegal shift or illegal
motion calls. The head linesman also rules on out-of-bounds calls that
happen on his side of the field, oversees the chain crew and marks the
forward progress of a runner when a play has been whistled dead.
A modern down indicator box is mounted on a pole and is used to mark
the current line of scrimmage. The number on the marker is changed
using a dial.
The side judge is positioned twenty yards downfield of the head
linesman. He mainly duplicates the functions of the field judge. On
field goal and extra point attempts, he is positioned lateral to the
The line judge is positioned on the end of the line of scrimmage,
opposite the head linesman. He or she supervises player substitutions,
the line of scrimmage during punts, and game timing. He notifies the
referee when time has expired at the end of a quarter and notifies the
head coach of the home team when five minutes remain for halftime. In
the NFL, the line judge also alerts the referee when two minutes
remain in the half. If the clock malfunctions or becomes inoperable,
the line judge becomes the official timekeeper.
The field judge is positioned twenty yards downfield from the line
judge. He monitors and controls the play clock, counts the number of
defensive players on the field, and watches for offensive pass
interference and illegal use-of-hands violations by offensive players.
He also makes decisions regarding catches, recoveries, the ball spot
when a player goes out of bounds, and illegal touching of fumbled
balls that have crossed the line of scrimmage. On field goal and extra
point attempts, the field judge is stationed under the upright
opposite the back judge.
The center judge is an eighth official used in the top level of
college football. He stands lateral to the referee, the same way the
umpire does in the NFL. The center judge is responsible for spotting
the football after each play, and has many of the same
responsibilities as the referee, except announcing penalties.
Another set of officials, the chain crew, are responsible for moving
the chains. The chains, consisting of two large sticks with a
10-yard-long chain between them, are used to measure for a first down.
The chain crew stays on the sidelines during the game, but if
requested by the officials they will briefly bring the chains on to
the field to measure. A typical chain crew will have at least three
people – two members of the chain crew will hold either of the two
sticks, while a third will hold the down marker. The down marker, a
large stick with a dial on it, is flipped after each play to indicate
the current down, and is typically moved to the approximate spot of
the ball. The chain crew system has been used for over 100 years and
is considered to be an accurate measure of distance, rarely subject to
criticism from either side.
American football protective equipment, Health issues in
American football, and Chronic traumatic encephalopathy
Vince Agnew wearing a helmet.
Shoulder pads and thigh pads are visible
under his uniform.
Football is a full-contact sport, and injuries are relatively common.
Most injuries occur during training sessions, particularly ones that
involve contact between players. To try to prevent injuries,
players are required to wear a set of equipment. At a minimum players
must wear a football helmet and a set of shoulder pads, but individual
leagues may require additional padding such as thigh pads and guards,
knee pads, chest protectors, and mouthguards. Most
injuries occur in the lower extremities, particularly in the knee, but
a significant number also affect the upper extremities. The most
common types of injuries are strains, sprains, bruises, fractures,
dislocations, and concussions.
Repeated concussions (and possibly sub-concussive head impacts)
can increase a person's risk in later life for chronic traumatic
encephalopathy and mental health issues such as dementia, Parkinson's
disease, and depression.
Concussions are often caused by
helmet-to-helmet or upper-body contact between opposing players,
although helmets have prevented more serious injuries such as skull
fractures. Various programs are aiming to reduce concussions by
reducing the frequency of helmet-to-helmet hits; USA Football's "Heads
Up Football" program is aiming to reduce concussions in youth football
by teaching coaches and players about the signs of a concussion, the
proper way to wear football equipment and ensure it fits, and proper
tackling methods that avoid helmet-to-helmet contact. However, a
study in the Orthopaedic Journal of Sports Medicine found that Heads
Football was ineffective; the same study noted that more extensive
reforms implemented by
Pop Warner Little Scholars
Pop Warner Little Scholars and its member teams
were effective in significantly reducing concussion rates.
Leagues and tournaments
National Football League
National Football League (NFL) and the National Collegiate
Athletic Association (NCAA) are the most popular football leagues in
the United States. The
National Football League
National Football League was founded in
1920 and has since become the largest and most popular sport in
the United States. The NFL has the highest average attendance of
any sporting league in the world, with an average attendance of 66,960
during the 2011 NFL Season. The NFL championship game is called
the Super Bowl, and is among the biggest events in club sports
worldwide. It is played between the champions of the National
Football Conference (NFC) and the
American Football Conference
American Football Conference (AFC),
and its winner is awarded the Vince Lombardi Trophy.
College football is the third-most popular sport in the United States,
behind professional baseball and professional football. The NCAA,
the largest collegiate organization, is divided into three Divisions:
Division I, Division II and Division III. Division I football is
further divided into two subdivisions: the
Football Bowl Subdivision
(FBS) and the
Football Championship Subdivision
Football Championship Subdivision (FCS). The
champions of each level of play are determined through NCAA-sanctioned
playoff systems; while the champion of Division I-FBS was historically
determined by various polls and ranking systems, the subdivision
adopted a four-team playoff system in 2014.
High school football
High school football is the most popular sport in the United States
played by boys; over 1.1 million boys participated in the sport
from 2007 to 2008 according to a survey by the National Federation of
State High School Associations (NFHS). The NFHS is the largest
organization for high school football, with member associations in all
50 states as well as the District of Columbia.
USA Football is the
governing body for youth and amateur football, and Pop Warner
Little Scholars is the largest organization for youth football.
Rival professional leagues
Several professional football leagues have been formed as rival
leagues to the NFL. The most successful rival league was the American
Football League (AFL), which existed from 1960 to 1969. The AFL became
a significant rival in 1964 before signing a five-year,
US$36 million television deal with NBC. AFL teams began to sign
NFL players to contracts, and the league's popularity grew to
challenge that of the NFL. The two leagues merged in the 1970 season,
and all AFL teams joined the NFL. An earlier league, the All-America
Football Conference, was in play from 1946 to 1949. After the league
dissolved, two AAFC teams, the
Cleveland Browns and the San Francisco
49ers, became members of the NFL; another member, the Baltimore Colts
joined the league, but folded after just a year in the NFL.
Other attempts to start rival leagues have been far less successful.
World Football League
World Football League (WFL) played for two seasons, in 1974 and
1975, but faced monetary issues so severe that the league could not
pay its players. In its second and final season the WFL attempted to
establish a stable credit rating, but the league disbanded before its
second season could be completed. The United States Football
League (USFL) operated for three seasons from 1983 to 1985 but
collapsed due to poor business decisions and monetary problems. A
subsequent USD $1.5 billion antitrust lawsuit against the NFL was
successful in court, but the league was awarded only three dollars in
XFL was created in 2001 by
Vince McMahon and lasted
for only one season. Despite television contracts with
high expectations, the
XFL suffered from poor television ratings and a
low quality of play. The United
Football League (UFL) began in
2009, but folded after suspending its 2012 season, due to financial
Players with one of the youth divisions of the Borregos Salvajes
football program of the Monterrey Institute of Technology and Higher
Education, Mexico City.
American football leagues exist throughout the world, but the game has
yet to achieve the international success and popularity of baseball
and basketball. NFL Europa, the developmental league of the NFL,
operated from 1991 to 1992 and then from 1995 to 2007. At the time of
its closure, NFL Europa had five teams based in Germany and one in the
European Football League
European Football League (EFL), run by the European Federation of
Football (EFAF), is an annual invitational tournament between
the champions or co-champions of competitions run by EFAF members. The
league's championship game is the Eurobowl. Other EFAF
tournaments include the EFAF Cup, played between the top teams from
national leagues in a similar manner to the UEFA Cup, the
Atlantic Cup, played between teams from the Atlantic region of
Europe, and the Challenge Cup, played between teams from newer
federations that are not eligible to play in the EFL or EFAF Cup.
American football federations are also present in Asia, Oceania, and
Pan America, and a total of 64 national football federations exist as
of July 2012. The International Federation of American Football
(IFAF), an international body composed of American football
federations, runs tournaments such as the IFAF World Championship,
which is held every four years since 1999, the IFAF Women's World
Championship, the IFAF U-19 World Championship and the Flag Football
World Championship. The IFAF also organizes the annual International
Bowl game. At the international level, Canada, Mexico, and Japan
are considered to be second-tier, while Austria, Germany, and France
would rank among a third tier. All of these countries rank far below
the United States, which is dominant at the international level.
Football is not an Olympic sport, but it was a demonstration sport at
the 1932 Summer Olympics. The IFAF has received provisional
recognition from the
International Olympic Committee
International Olympic Committee (IOC), and a vote
on making it an
Olympic sport could be held as early as 2017.
Several major obstacles hinder the IFAF goal of achieving status as an
Olympic sport, such as the predominant participation of men in
international play and the short three-week Olympic schedule. Large
team sizes are an additional difficulty, due to the Olympics' set
limit of 10,500 athletes and coaches.
American football also has the
issue of global visibility. Nigel Melville, the CEO of USA Rugby,
noted that "
American football is recognized globally as a sport, but
it's not played globally." In order to solve these concerns, major
effort has been put into promoting flag football, a modified version
of American football, at the international level.
Popularity and cultural impact
American football in the United States
Baseball is still called the national pastime, but football is by far
the more popular sport in American society", according to ESPN.com's
Sean McAdam. In a 2014 poll conducted by Harris Interactive,
professional football ranked as the most popular sport, and college
football ranked third behind only professional football and baseball;
46% of participants ranked some form of the game as their favorite
sport. Professional football has ranked as the most popular sport in
the poll since 1985, when it surpassed baseball for the first
time. Professional football is most popular among those who live
in the eastern United States and rural areas, while college football
is most popular in the southern United States and among people with
graduate and post-graduate degrees.
Football is also the
most-played sport by high school and college athletes in the United
States. In a 2012 study, the NCAA estimated there were around
1.1 million high school football players and nearly 70,000
college football players in the United States; in comparison, the
second-most played sport, basketball, had around 1 million
participants in high school and 34,000 in college. The Super Bowl
is the most popular single-day sporting event in the United
States, and is among the biggest club sporting events in the world
in terms of TV viewership. The NFL makes approximately
$10 billion annually.
Super Bowl games account for seven of
the top eight most-watched broadcasts in American history; Super Bowl
XLIX was watched by a record 114.4 million Americans.
American football also plays a significant role in American culture.
Super Bowl is considered a de facto national holiday, and in
parts of the country like Texas, the sport has been compared to a
Football is also linked to other holidays; New
Year's Day is traditionally the date for several college football bowl
games, including the Rose Bowl. However, if New Year's Day is on a
Sunday, the bowl games are moved to another date to not conflict with
the typical NFL Sunday schedule. Thanksgiving football is an
American tradition, hosting many high school, college, and
professional games. Steve Deace of
USA Today wrote that Americans
are passionate about football "because it embodies everything we love
about American exceptionalism. Merit is rewarded, not punished.
Masculinity is celebrated, not feminized. People of various beliefs
and backgrounds – a melting pot, if you will – must unify for a
common goal for the team to be successful". Implicit rules such
as playing through pain and sacrificing for the better of the team are
promoted in football culture.
The safety of the sport has also sparked national controversy in
American popular culture. It is often received as "overly
aggressive", and defamiliarized in popular culture. The 2015 film
Concussion aimed to shed light on the sport's safety, specifically in
the NFL by having
Will Smith portray Dr. Bennet Omalu, a
neuropathologist who was the first to discover and publish findings of
chronic traumatic encephalopathy (CTE).
In Canada, the game has a significant following – according to a
2013 poll, 21% of respondents said they followed the NFL "very
closely" or "fairly closely", making it the third-most followed league
National Hockey League
National Hockey League (NHL) and Canadian
American football also has a long history in Mexico, which
was introduced to the sport in 1896.
American football was the
second-most popular sport in Mexico in the 1950s, with the game being
particularly popular in colleges. The
Los Angeles Times
Los Angeles Times notes
that the NFL claims over 16 million fans in Mexico, which places the
country third behind the US and Canada.
American football is
played in Mexico both professionally and as part of the college sports
system. The top
American football competition in Mexico is the
Liga de Fútbol Americano Profesional
Liga de Fútbol Americano Profesional (Professional
Football League). At the collegiate level there is the Liga
Mayor of the ONEFA, a college championship founded in 1930. There is
also the CONADEIP Premier Conference, another college competition
founded in 2010.
American football is the fifth most popular sport in
Mexico and the country has the highest rating of the NFL outside the
Opening ceremony of the 2010
NFL International Series
NFL International Series at London's
Japan was introduced to the sport in 1934 by Paul Rusch, a teacher and
Christian missionary who helped establish football teams at three
universities in Tokyo. Play was halted during World War II, but began
to grow in popularity again after the war. As of 2010[update], there
are more than 400 high school football teams in Japan, with over
15,000 participants, and over 100 teams play in the Kantoh Collegiate
Football Association (KCFA). The college champion plays the
champion of the
X-League (a semi-pro league where teams are financed
by corporations) in the
Rice Bowl to determine Japan's national
Europe is a major target for expansion of the game by football
organizers. In the United Kingdom in the 1980s, the sport was fairly
popular, with the 1986
Super Bowl being watched by over 4 million
people (about 1 out of every 14 Britons). The sport's popularity faded
over the 1990s, coinciding with the establishment of the Premier
League. According to
BBC America, there is a "social stigma"
American football in the UK, with many Brits feeling the
sport has no right to call itself 'football' due to the small emphasis
on kicking. Nonetheless, the sport has retained a following in
the United Kingdom; the NFL operates a media network in the country,
and since 2007 has hosted the
NFL International Series
NFL International Series in London.
Super Bowl viewership has also rebounded, with over 4.4 million
Super Bowl XLVI.
The sport is played in European countries such as Switzerland, which
American football clubs in every major city, and Germany,
where the sport has around 45,000 registered amateur players. In
Europe, almost all nations have their own leagues, highlighting its
importance those of
Football League), Germany
Football League), France (Ligue Élite de
and Italy (Italian
Football League). But in these countries American
football has not yet reached the same level of popularity it has, for
example, in North America. There are national teams of Austria,
Finland, France, Germany, Great Britain, Hungary, Israel, Italy,
Netherlands, Poland, Romania, Russia, Serbia, Spain and Sweden.
American football audience increased 800% between 2013 and
2016, according to ESPN, which is, along to Esporte Interativo, the
responsible to the transmission in the country. Brazil's audience is
the 3rd of the world, behind only Mexico and United States. NFL
leaders visited Maracanã Stadium, in Rio de Janeiro, to verify the
field. Rumors were that a
Pro Bowl edition could be held there. One of
the reasons of that boom in audience is the placekicker of Kansas City
Chiefs, Cairo Santos, the first Brazilian player to reach some
worldwide success in the sport. Also, the sport is already one of
the most played around the country, with approximately 130 teams. The
Superliga Nacional de Futebol Americano (National American Football
Superleague) is a recently created Brazilian
American football league,
created and organized by the Confederação Brasileira de Futebol
Americano (pt) (Brazilian Confederation of American Football). To
2017, a strongest league will get start in June, including 32 teams
around the country, in 4 conferences. In 2017, the famous soccer team
Cruzeiro Esporte Clube
Cruzeiro Esporte Clube joined with the 2016 America Cup's champion BH
Eagles Futebol Americano, to create the Sada Cruzeiro Futebol
Americano. The recent born team already won his state championship,
and for the Brazilian top league already has signed with former NFL's
player Nic Harris.
In other countries of South America there was a very important
evolution with regard to American Football, since 2006 when has begun
the practice of this sport in Argentina. Currently there are three
Football Leagues in that country:
Argentina, located in Buenos Aires, which has six teams; Córdoba
Football Americano, located in Córdoba, with three teams; Rosario
Football League, located in Rosario, also with three teams. In
addition there are teams in the formation stage in several provinces,
such as in the province of Santa Fe.
Colombia the FECOFA (Colombian Federation of American Football) was
created. Recently it formalized a strategic alliance with FLAG
FOOTBALL COLOMBIA to join efforts and work together looking for the
growth and development of
American football in all its modalities.
Variations and related sports
See also: Canadian football, Arena football, and Flag football
Men playing a game of flag football
Canadian football, the predominant form of football in Canada, is
closely related to
American football – both sports developed from
rugby, and the two sports are considered to be the chief variants of
gridiron football. Although the two games share a similar set of
rules, there are several key rule differences: for example, in
Canadian football the field measures 150 by 65 yards (137 by
59 m), including two 20-yard end zones (for a distance between
goal lines of 110 yards), teams have three downs instead of four,
there are twelve players on each side instead of eleven, fair
catches are not allowed, and a rouge, worth a single point is scored
if the offensive team kicks the ball out of the defense's end
Canadian Football League
Canadian Football League (CFL) is the major Canadian
league and is the second-most popular sporting league in Canada,
behind only the National
A major variant of football is arena football, played by the Arena
Football League (AFL).
Arena football has eight-player teams and
uses an indoor field 50 yards (46 m) in length, excluding end
zones, and 28.3 yards (25.9 m) wide. Punting is illegal, and
kickoffs are attempted from the goal line. Large overhead nets deflect
forward passes and kicks that hit them, and deflected kicks are live
balls that may be recovered by either team.
Arena Football League
Arena Football League are what
New York Times
New York Times writer Mike
Tanier described as the "most minor of minor leagues:" indoor football
leagues. Like in arena football, teams in indoor football leagues play
in arenas, but games are only attended by a small number of fans, and
most players are semi-professional athletes.
Indoor football leagues
are unstable, with franchises regularly moving from one league to
another or merging with other teams, and teams or entire leagues
dissolving entirely. The
Football League, National Arena
Champions Indoor Football
Champions Indoor Football and American Arena League are
examples of prominent indoor leagues that are active as of 2017.
There are several non-contact variants of American football, such as
flag football. In flag football the ballcarrier is not tackled;
instead, defenders aim to pull a flag tied around his waist.
Another variant, touch football, simply requires the ballcarrier to be
touched to be considered downed. A game of touch football may require
that the player be touched with either one or two hands to be
considered down, depending on the rules used.
American football portal
American football strategy
American football and rugby union
American football and rugby league
Concussions in American football
Fantasy football (American)
Glossary of American football
American football players
American football stadiums by capacity
List of leagues of American and Canadian football
Football Hall of Fame
Steroid use in American football
^ a b Florio, Mike (July 27, 2012). "
Football remains an Olympic long
NBC Sports. Retrieved January 14,
^ "Gridiron", MacMillan Dictionary
^ "gridiron football (sport)". Britannica Online Encyclopedia.
britannica.com. Retrieved 13 July 2010.
^ "The Official Site of Rutgers Athletics".
^ Peralta, Eyder (June 10, 2010). "
Football Or Soccer? What's in a
Name?". NPR. Retrieved April 19, 2014.
^ Geoghegan, Tim (May 27, 2013). "'In the six' and football's other
BBC News. Retrieved June 28, 2013.
^ Huntsdale, Justin (June 13, 2012). "Living off the grid: American
football in coastal Australia". Australian Broadcasting Company.
Retrieved June 28, 2013.
^ "The basics of rugby union". BBC. Retrieved April 19, 2014.
^ "Rutgers – The Birthplace of Intercollegiate Football". Rutgers
University. Archived from the original on September 24, 2014.
Retrieved November 24, 2012.
^ a b c "No Christian End! The Beginnings of
Football in America"
Football Researchers Association. Retrieved
November 24, 2012.
^ a b c d e "Camp and His Followers" (PDF). Professional Football
Researchers Association. Retrieved November 24, 2012.
^ a b "NFL History 1869–1910". NFL.com. Archived from the original
on January 2, 2008. Retrieved November 24, 2012.
^ Bennett (1976), p. 20.
^ Lewis, Guy M. (1969). "Teddy Roosevelt's Role in the 1905 Football
Controversy". The Research Quarterly. 40: 717–724.
^ "The History of the NCAA". National Collegiate Athletic Association.
Archived from the original on April 30, 2007. Retrieved November 24,
^ Braunwart, Bob; Carroll, Bob. "Blondy Wallace and the Biggest
Football Scandal Ever: 1906" (PDF). The Coffin Corner. Professional
Football Researchers Association. Archived from the original (PDF) on
September 28, 2014. Retrieved November 25, 2012.
^ "NFL History 1911–1920". NFL.com. Archived from the original on
January 15, 2008. Retrieved November 24, 2012.
^ Danzig, Allison (1956). The History of American Football: Its Great
Teams, Players, and Coaches. Englewood Cliffs, N.J.: Prentice-Hall.
^ Vancil (2000), p. 22.
^ "The Birth of Pro Football". Pro
Football Hall of Fame. Archived
from the original on November 16, 2006. Retrieved March 19,
^ a b Clary, Jack (1994). "The First 25 Years" (PDF). The Coffin
Football Researchers Association. 16 (4): 1,
4–5. Archived from the original (PDF) on September 28, 2014.
^ Jozsa (2004), pp. 270.
^ Nelson, Robert (January 11, 2007). "The Curse". Phoenix New Times.
Retrieved January 30, 2013.
^ "Greatest game ever played". Pro
Football Hall of Fame. Retrieved
March 20, 2013.
^ a b Clary, Jack (1994). "The Second 25 Years" (PDF). The Coffin
Football Researchers Association. 16 (5): 4–5.
Archived from the original (PDF) on October 19, 2014.
^ "BCS Chronology". FOX Sports on MSN. 2006. Archived from the
original on January 13, 2010. Retrieved March 19, 2013.
^ Wojciechowski, Jean (June 26, 2012). "Presidents get playoff plan
right". ESPN.com. Retrieved March 20, 2013.
^ Ralph D. Russo (January 2, 2015). "NCAA College
pits powerhouses Ohio State and Oregon". Toronto Star. Retrieved
January 16, 2015.
^ a b c NFL Rules 2012, p. 21.
^ a b NCAA Rules 2011–2012, p. 15.
^ NFHS Rules 2012, p. 11.
^ NCAA Rules 2011–2012, p. 107.
^ NFHS Rules 2012, pp. 71–72.
^ NFL Rules 2012, pp. 21–22.
^ NCAA Rules 2011–2012, pp. 53–54.
^ NFHS Rules 2012, pp. 45–46.
^ Dickson, James David (July 14, 2010). "The innovator". Michigan
Today. Archived from the original on October 19, 2013. Retrieved
October 7, 2012.
^ NCAA Rules 2011–2012, pp. 21–22.
^ NFHS Rules 2012, pp. 16–17.
^ a b c d e f "NFL in a nutshell".
BBC Sport. October 19, 2005.
Retrieved November 20, 2012.
^ NFL Rules 2012, pp. 21–24.
^ NFHS Rules 2012, pp. 57–58.
^ NFL Rules 2012, pp. 36, 40.
^ Long, Howie; Czarnecki, John. "Common Penalties in American
Football". Dummies.com. Retrieved November 23, 2012.
^ a b c d e f g h "
Football Players' Roles in Team Offense and
Defense". Dummies.com. Retrieved January 14, 2013.
^ Pasquarelli, Len (June 1, 2010). "Fullbacks back en vogue".
ESPN.com. Retrieved November 22, 2012.
^ Wood, Ryan. "Centers: The Unsung Heroes of Football". Active.com.
Retrieved November 22, 2012.
^ Long, Howie; Czarnecki, John. "Football's Offensive Team: The
Receivers". Dummies.com. Retrieved November 22, 2012.
^ Long, Howie; Czarnecki, John. "Football's Defensive Team: The
Linebackers". Dummies.com. Retrieved November 23, 2012.
^ Long, Howie; Czarnecki, John. "The Role of
Special Teams in a
Football Game". Dummies.com. Retrieved January 12, 2012.
^ Long, Howie; Czarnecki, John. "
Special Teams: Players on a
Punt Team". Dummies.com. Retrieved January 12, 2012.
^ a b c Sackrowitz, Harold (2000). "Refining the
Touchdown Decision" (PDF). Department of Statistical
Science. Duke University. 13 (3): 29–30, 33–34. Retrieved October
^ NFL Rules 2012, p. 56–57.
^ NCAA Rules 2011–2012, pp. 77–79.
^ NFHS Rules 2012, pp. 65–66.
^ a b NFL Rules 2012, pp. 57–59.
^ a b NCAA Rules 2011–2012, pp. 79–80.
^ a b NFHS Rules 2012, p. 66.
^ a b c "Beginner's Guide to Football". National
Retrieved September 30, 2012.
^ NFL Rules 2012, p. 60
^ NFL Rules 2012, p. v, 1.
^ NCAA Rules 2011–2012, pp. 18–19, 23–24.
^ NFHS Rules 2012, pp. 11–12, 13, 28.
^ a b NFL Rules 2012, p. 2.
^ a b NCAA Rules 2011–2012, p. 18.
^ a b c d NFHS Rules 2012, p. 14.
^ Cross, Rod (August 2010). "Bounce of an oval shaped football".
Sports Technology. 3 (3): 168–180. doi:10.1080/19346182.2011.564283.
Retrieved April 23, 2014.
^ a b NCAA Rules 2011–2012, p. 20.
^ NFL Rules 2012, p. 3.
^ "Official Playing Rules of the National
Football League" (PDF).
Archived from the original (PDF) on March 3, 2016. , p.3
^ a b c NFL Rules 2012, p. 14.
^ a b NCAA Rules 2011–2012, p. 45.
^ NFHS Rules 2012, pp. 38–39.
^ NFHS Rules 2012, p. 39.
^ Easterbrook, Gregg (September 4, 2008). "TMQ's all-haiku NFL
preview". ESPN.com. Retrieved October 1, 2013.
Football Game Time Is Measured in Quarters". Dummies.com.
Retrieved December 2, 2012.
^ a b NFL Rules 2012, pp. 14–18
^ NCAA Rules 2011–2012, pp. 47–53.
^ NFHS Rules 2012, pp. 38–45
^ McCarthy, Michael (October 27, 2011). "Delay of game: NFL games
running longer in 2011". USA Today. Retrieved December 3, 2012.
^ NCAA Rules 2011–2012, pp. 16, 41.
^ NCAA Rules 2011–2012, pp. 41, 46–47.
^ NFHS Rules 2012, pp. 36, 45.
^ Smith, Michael David (November 16, 2013). "When a runner's helmet
comes off, he's down". Profootballtalk.com. Retrieved October 19,
^ a b Branch, John (December 31, 2008). "The Orchestration of the
Chain Gang". The New York Times. Retrieved December 19, 2012.
^ St. John, Allan (December 18, 2009). "The Tech Behind the Football's
Broadcast-Only First Down Line". Popular Mechanics. Retrieved November
^ a b c Hogrogian, John (1999). "The Last Drop Kick?" (PDF). The
Coffin Corner. Professional
Football Researchers Association. 21 (6).
Retrieved October 22, 2012.
^ a b "The last dropkick". Pro
Football Hall of Fame. Retrieved
October 8, 2012.
^ NFL Rules 2012, p. 50.
^ a b NCAA Rules 2011–2012, p. 34.
^ NFHS Rules 2012, p. 32.
^ NFL Rules 2012, p. 6.
^ NCAA Rules 2011–2012, p. 30.
^ NFHS Rules 2012, p. 27.
^ NFL Rules 2012, pp. 8–9.
^ NFHS Rules 2012, pp. 31–32.
^ NFL Rules 2012, pp. 29–30.
^ NCAA Rules 2011–2012, pp. 61–64.
^ NFHS Rules 2012, pp. 15, 46, 52–53.
^ NFL Rules 2012, pp. 33–34, 50–53.
^ NCAA Rules 2011–2012, pp. 55–56, 63–64.
^ NFHS Rules 2012, pp. 49, 53–54.
^ NFL Rules 2012, pp. 7, 54–55.
^ NCAA Rules 2011–2012, pp. 30, 66–67.
^ NFHS Rules 2012, pp. 27, 56.
^ a b Long, Howie; Czarnecki, John. "American
Dummies.com. Retrieved November 22, 2012.
^ a b Saal JA (August 1991). "Common
American football injuries".
Sports Medicine. 12 (2): 132–47.
doi:10.2165/00007256-199112020-00005. PMID 1947533.
^ NFL Rules 2012, pp. 24–27.
^ NCAA Rules 2011–2012, p. 22.
^ NFHS Rules 2012, pp. 17–19.
^ Repeated Head Hits, Not Just Concussions, May Lead To A Type Of
Chronic Brain Damage
^ Maiese, Kenneth (January 2008). "Concussion". The Merck Manual Home
– Health Handbook.
^ Gregory, Sean (October 22, 2010). "Can
Football Finally Tackle Its
Injury Problem?". Time Magazine. Retrieved January 16, 2013.
^ "Heads Up Football". USA Football. Retrieved September 20,
^ N.F.L.-Backed Youth Program Makes Unsupported Concussion Safety
Claims By ALAN SCHWARZ, New York Times, July 27, 2016
^ Fentress, Andrew (May 18, 2012). "New version of United States
Football League aims to succeed where others have failed". Oregon
Live. Advance Internet. Retrieved January 9, 2013.
^ "NFL founded in Canton". Pro
Football Hall of Fame. Retrieved
November 26, 2012.
^ Chin, Andrew (November 25, 2012). "China fast catching American
football fever with 10 teams formed". South China Morning Post.
Retrieved November 26, 2012.
^ "And the silver goes to ..." The Economist. September 27, 2011.
Retrieved December 6, 2012.
^ a b Harris, Nick (January 31, 2010). "Elite clubs on Uefa gravy
Super Bowl knocked off perch". The Independent. Retrieved
November 28, 2012.
^ George, Shannon (September 10, 2009). "Let's Learn About: The Vince
Lombardi Trophy". Pittsburgh Post-Gazette. Retrieved January 9,
Football is America's Favorite
Sport as Lead Over Baseball
Continues to Grow". Harris Interactive. January 25, 2005. Retrieved
November 26, 2012.
^ "About the NCAA". NCAA.org. Archived from the original on January
18, 2013. Retrieved January 9, 2013.
^ "Differences Among the Three Divisions: Division I". NCAA.org.
Archived from the original on November 4, 2013. Retrieved January 9,
^ "Postseason Football". NCAA.org. Archived from the original on May
22, 2012. Retrieved January 9, 2013.
^ Alic, Steve (April 4, 2009). "NFHS and
USA Football Create Football
Coaching Course". USA Football. Retrieved October 5, 2013.
^ O'Connor, Anahad (June 12, 2012). "Trying to Reduce Head Injuries,
Football Limits Practices". The New York Times. Retrieved
October 5, 2013.
^ Cross, B. Duane (January 22, 2001). "Off-the-field competition
yields game-changing merger". CNNSI. Archived from the original on
October 19, 2013. Retrieved February 15, 2013.
^ Johnson, William Oscar (December 1, 1975). "The Day The Money Ran
Out". Sports Illustrated. Archived from the original on October 19,
2013. Retrieved March 25, 2013.
^ Somers, Kent (August 7, 2008). "Twenty years later, USFL still
brings fond memories". USA Today. Retrieved March 25, 2013.
^ Sandomir, Richard (May 11, 2001). "No More Springtimes for the XFL
as League Folds". The New York Times. Retrieved January 20,
^ Keiser, Thomas (October 20, 2012). "Just What Is Going on with the
UFL?". International Business Times. Retrieved January 20, 2013.
^ Nelson 1993, p. 15.
^ "NFL Europa to cease operations". NFL.com. June 29, 2007. Archived
from the original on July 3, 2007. Retrieved January 9, 2013.
European Football League
European Football League EFL". European Federation of American
Football. Retrieved January 9, 2013.
^ "EFAF Cup". European Federation of American Football. Retrieved
January 9, 2013.
^ "Atlantic Cup". European Federation of American Football. Retrieved
January 9, 2013.
^ "Challenge Cup". European Federation of American Football. Retrieved
January 9, 2013.
^ a b c Breer, Albert (July 26, 2012). "
Football in Olympics is a
dream that could become a reality". NFL.com. Retrieved March 21,
^ "Championship Competitions". International Federation of American
Football. Retrieved January 9, 2013.
^ Marvez, Alex (June 2, 2014). "
Football takes step toward Olympics,
could be medal sport in 2024". Foxsports.com. Archived from the
original on February 4, 2015. Retrieved June 18, 2015.
^ McAdam, Sean (February 10, 2004). "
Football leaving baseball in the
dust". ESPN.com. Retrieved April 17, 2014.
^ Rovell, Darren (January 26, 2014). "NFL most popular for 30th year
in row". ESPN.com. Retrieved March 20, 2013.
^ "As American as Mom, Apple Pie and Football?". Harris Interactive.
January 16, 2014. Retrieved April 27, 2014.
^ "Estimated Probability of Competing in Athletics Beyond the High
School Interscholastic Level" (PDF). NCAA.org. September 17, 2012.
Archived from the original (PDF) on April 26, 2014. Retrieved April
^ Schrotenboer, Brent (February 5, 2014). "NFL takes aim at
$25 billion, but at what price?". USA Today. Retrieved April 26,
^ Peralta, Eyder (February 2, 2015). "
Super Bowl XLIX Was Most Watched
Show in TV History". NPR. Retrieved June 18, 2015.
^ Flint, Joe (February 4, 2011). "NFL has made
Super Bowl Sunday into
a holiday, is a three-day weekend the next step?". Los Angeles
^ Brown, Bob. "In Texas, High School
Football Is King". ABC News.
Retrieved April 27, 2014.
^ Bishop, Greg (January 29, 2011). "A$60 Million Palace for
School Football". The New York Times. Retrieved April 27, 2014.
^ Wischnowsky, Dave (December 30, 2011). "No New Year's Day Bowl
Games? Bah, Humbug". CBS Chicago. Retrieved April 28, 2014.
^ Lee, Jolie (November 28, 2013). "From Macy's to NFL, Thanksgiving
traditions explained". USA Today. Retrieved April 28, 2014.
^ Bell, Danna (November 22, 2012). "Thanksgiving and Football: A
Unique American Tradition". Library of Congress. Retrieved April 28,
^ Deace, Steve (January 30, 2013). "
Football celebrates masculinity".
USA Today. Retrieved May 2, 2014.
^ Smith (2009), p. 146.
^ "Health issues in American football".. May 1, 2017.
^ "Why American
Football Is Stupid". Odyssey. November 24, 2015.
^ Spurrier, Guy (January 30, 2014). "
Super Bowl 2014: Comparing the
NFL's popularity in Canada and the U.S." National Post. Archived from
the original on May 25, 2017. Retrieved April 17, 2014.
^ Viruega, Pablo (October 1, 2008). "Mexico's long love affair with
football, American-style". ESPN.com. Retrieved April 17, 2014.
^ Baxter, Kevin (January 29, 2010). "NFL's popularity in Mexico
continues to grow". Los Angeles Times. Retrieved April 17, 2014.
^ a b "
American football touches down in Germany". The Local. January
27, 2013. Retrieved April 17, 2014.
^ Jardine, Lisa (September 28, 2010). "Friday night lights: American
football in Japan a high school hit". CNN Travel. Retrieved April 23,
^ "Obic captures third straight Rice Bowl". The Japan Times. January
3, 2013. Retrieved April 23, 2014.
^ Langford, John (February 17, 2014). "
Touchdown in the U.K.:
Britain's Long-Distance Affair with the NFL".
Anglophenia. Retrieved April 17, 2014.
^ Morrison, Sarah; Hayman-Brown, Isabel (February 5, 2012). "Super
Bowl caps UK's growing gridiron fever". The Independent. Retrieved
June 19, 2015.
^ Tagliabue, John (April 14, 2011). "The Game Is American, but the
View, Alpine". The New York Times. Retrieved April 17, 2014.
^ Macedo, Sandro (February 2, 2017). "Crescimento do interesse por
futebol americano no Brasil atrai NFL". Folha de S.Paulo. Retrieved
April 28, 2017.
^ "Gridiron football". Encyclopædia Britannica Online. pp. 1,
13–14. Retrieved January 10, 2013.
^ "Argos, Rogers Centre agree on lease deal through 2017". CBC Sports.
September 20, 2013. Retrieved April 19, 2014.
^ Staples, Andy (June 28, 2013). "Behind IDFFL, Canadian players chase
football dreams". Sports Illustrated. Archived from the original on
April 20, 2014. Retrieved April 19, 2014.
^ a b Buchinski, Colin; Neu, Dietrich (January 6, 2011). "Head to
Head: CFL vs. NFL". The Carillon. Retrieved January 10, 2013.
^ Colston, Chris (April 15, 2007). "Arena football: Is it America's
fifth major sport?". USA Today. Retrieved January 10, 2013.
^ "Arena football: The basics". USA Today. April 13, 2007. Retrieved
January 10, 2013.
^ Tainer, Mike (June 27, 2011). "Staying in the Game on Football's
Fringe". The New York Times. Retrieved January 19, 2013.
^ Mills, Amy (July 30, 2013). "NFL FLAG football is about fun and
fundamentals". USA Football. Retrieved April 19, 2014.
^ Musto, Adam (March 19, 2012). "Proper flag pull takes fast feet and
discipline". USA Football. Retrieved April 19, 2014.
^ Gay, Jason. "The 32 Rules of Thanksgiving Touch Football". The Wall
Street Journal. Retrieved January 10, 2013.
^ The terms "gridiron football" and "gridiron" are sometimes used as
synonyms for American football, and are also sometimes used in a
broader sense that includes
Canadian football as well.
Bennett, Tom (1976). The Pro Style: The Complete Guide to
National Football League
National Football League Strategy. Los Angeles: National
Football League Properties, Inc., Creative Services Division.
Colgate, Bob, ed. (2011). "2011 NFHS
Football Rules Book" (PDF).
Gardener, Robert B.. NFHS Publications. Archived from the original
(PDF) on March 4, 2016.
Jozsa, Frank P. (2004). Sports Capitalism: The Foreign Business of
American Professional Leagues. Ashgate Publishing.
Nelson, David M. (December 12, 1993). The Anatomy of a Game: Football,
the Rules, and the Men Who Made the Game (1 ed.). University of
Delaware Press. p. 15. ISBN 978-0-87413-455-1.
"Official Playing Rules and Casebook of the National
Football League. 2012.
Redding, Rogers (2011–2012). Halpin, Ty, ed. "NCAA
and Interpretations" (PDF). National Collegiate Athletic Association.
Smith, Earl, ed. (August 11, 2009). Sociology of
Sport and Social
Theory. Human Kinetics. ISBN 978-0-7360-7572-5.
Vancil, Mark (Ed.) (2000). ABC Sports College
All-America Team. New York: Hyperion Books.
Football: Great Writing About the National Sport, edited by John
Schulian; 2014 (New York: Library of America)
Listen to this article (info/dl)
This audio file was created from a revision of the article "American
football" dated July 5, 2014, and does not reflect subsequent edits to
the article. (Audio help)
More spoken articles
Find more aboutAmerican footballat's sister projects
Definitions from Wiktionary
Media from Wikimedia Commons
News from Wikinews
Quotations from Wikiquote
Texts from Wikisource
Textbooks from Wikibooks
Travel guide from Wikivoyage
Data from Wikidata
American football at Curlie (based on DMOZ)
International Federation of American Football
NFL 360, an introductory website to football rules
Excerpts of a 1903 football game between the University of Chicago and
University of Michigan
International American football
Women's World Championship
U-19 World Cup
World University Championship
World Games (demonstration)
IFAF Europe: European Championship
European Junior Championship
EFAF Challenge Cup
EFAF Euro Top 20
Gridiron football concepts
Rules of gridiron football codes
Levels of play
Line of scrimmage
Field goal range
Turnover on downs
Fourth down conversion
Running out the clock
Total quarterback rating
Yards after catch
Yards from scrimmage
Official (American, Canadian)
Running up the score
Australian rules football
Circle rules football
Indoor American football
Eton wall game
International rules football
Medieval football codes
Uppies and downies
Stick and ball sports
Indigenous North American stickball
Balle à la main
Ballon au poing
Ice stock sport
Tug of war