- American Football

American Football is a game played on a rectangular field by two opposing teams with an inflated leather ball that is roughly oval in shape. The object of the game is to score points by carrying the ball across the opponent's goal line or by kicking the ball through the opponent's goal posts. Football is considered a full-contact sport, meaning that play involves bodily contact by way of checking, blocking, grabbing, and tackling. Because of the rough physical nature of the game, playing football can cause injuries.

American football is a distinct type of football that developed in the United States in the 19th century. It developed from soccer (association football) and rugby football. American football differs slightly in rules and field size from a style of football played mostly in Canada, called Canadian football.

Played by professionals and amateurs (generally male high school and college students), football is one of the most popular American sports, attracting thousands of participants and millions of spectators annually. The sport's premier event is the championship game of the

National Football League (NFL), which is called the Super Bowl. Held each January, the game is attended by more than 60,000 fans and watched by more than 130 million television viewers in the United States.

American Football Field

The football field, sometimes called the gridiron, measures 120 yd (110 m) in length and 160 ft (about 49 m) in width. The 100-yd-long main body of the playing field is divided horizontally in 5-yd intervals with hash marks delineating individual yards. Areas used for scoring, called end zones, are located at each end of the field.

Football can be played on a variety of surfaces, including grass, dirt, and artificial turf. An NFL-regulation playing field measures 120 yd (110 m) long and 53 yd 1 ft (48.8 m) wide. At both ends of the 100-yd main body of the playing field, white lines called goal lines mark off the entrances to the end zones, which are 10 yd (9 m) deep. Each team defends one end zone. To score, a team must carry, pass, or kick the ball into the opponent's end zone. Lines parallel to the end zones cross the main body of the field at 5-yd (4.5-m) intervals. These lines give the field a resemblance to a large gridiron. Sets of lines called the sidelines run along both sides of the field. In addition, two sets of short lines, called hash marks, run down the field at 1 yd (.9 m) intervals. The hash marks are 53 ft 4 in (16.3 m) from each sideline in college and high school football, and 70 ft 9 in (21.6 m) from each sideline in the NFL. After each play, the officials place the ball either between the hash marks or on the hash mark closest to the end of the previous play. The next play begins from that spot.

Situated in the middle of the rear line of each end zone are goalposts, consisting of a 10-ft (3-m) vertical pole topped by a horizontal crossbar. Two vertical posts extend up from the crossbar, 18 ft 6 in (5.6 m) apart. Kickers score extra points (worth one point) and field goals (worth three points) by kicking the ball above the crossbar and between the posts.

Football is played by two opposing teams, each fielding 11 players. Each team tries to move the ball down the field to score in the end zone defended by its opponents. During a football game the teams are designated as the offensive team (the team in possession of the ball) and the defensive team (the team defending a goal line against the offensive team). Another group of players, called special teams, enter the game when possession of the ball changes, or when a field goal or extra point is attempted. At the professional level, players usually specialize at one position. At colleges and high schools, players sometimes play both offense and defense, or play on special teams in addition to their regular position.

The 11 players of the offensive team work together to move the ball downfield toward their opponent's end zone. They are divided into two groups: seven linemen, who play on the line of scrimmage (an imaginary line designating the position of the ball) and a backfield of four players, called backs, who stand in various positions behind the linemen. The lineman who is positioned in the middle of the line is called the center. On his left is the left guard and on his right is the right guard. On the left of the left guard is the left tackle, and on the right of the right guard is the right tackle. On the ends of the line are the tight end and the split end.

The center begins each play by hiking the ball, or passing it between his legs from a crouched position to the player standing directly behind him. (This action is also referred to as the snap.) After the ball is hiked on a running play, the center, guards, and tackles block defenders to create an open path for the ball carrier. On passing plays the linemen protect the quarterback and give him time to throw. Tight ends and split ends can block opponents, but they may also catch the ball during a passing play.

The back who usually stands directly behind the center and receives the snap is known as the quarterback. The quarterback directs the play of the offensive team by calling out each play. The quarterback may hand off the ball, pass it, or run with it downfield.

In a balanced backfield formation, or T-formation, the fullback stands behind the quarterback, and the left and right halfbacks stand to either side of the fullback. When the quarterback hands the ball off to one of these backs, that player rushes, or runs with the ball. Backs also block when the quarterback throws a pass. Many passes go to wide receivers, players who replace backs or ends and line up on the line of scrimmage but wide of the rest of the formation. They run down the field in planned pass routes to catch balls thrown by the quarterback.

The defensive players work together to prevent the offense from scoring. A row of linemen called the defensive line position themselves at the line of scrimmage; a row of linebackers position themselves about 5 yd (4.6 m) behind the defensive line; and a collection of defensive backs, called the secondary, stand on the end of the defensive line and behind the linebackers.

The defensive line can use any number of players, but most teams use three or four linemen. Defensive linemen principally are responsible for stopping the opposition's rushing attack and, in passing situations, putting pressure on the quarterback. Depending on the situation, linebackers stop runners, pressure the quarterback, or cover the opposition's receivers. Teams usually employ three or four linebackers. The secondary is composed of cornerbacks and safeties. These players cover receivers, tackle rushers who break down the field, and pressure the quarterback. The secondary commonly consists of two cornerbacks who defend the wide receivers and two safeties who guard the area behind the linebackers.

Each team has players who enter the game during special plays such as kickoffs, field goals, punts, and returns. The kicker kicks off at the beginning of a game or half, and after his team has scored. The kicker also scores points for the offensive team by kicking the ball through the goalpost uprights; these scores are called field goals. When the offensive team must surrender the ball to the opponents, a punter comes in to kick the ball downfield as far as possible toward the opponent's end zone. One player on the return team catches the kickoff or punt and runs upfield while the other return team players block for him. The return team tries to give the offense good starting field position.

Football Hand Signals

Football hand signals are often symbolic of the decision being given; for example, to signal a holding penalty, an official holds one wrist firmly with the other hand. Although the referee usually gives the signals, they can be given by any of the game officials.

A team of officials supervises play in a regulation game. Professional and major college football programs use seven officials: a referee, an umpire, a linesman, a field judge, a back judge, a line judge, and a side judge. The officials carry whistles and yellow penalty flags. They blow the whistles or throw the flags to indicate that an infraction of the rules has occurred.

The referee is in charge of the game at all levels of play. The referee supervises the other officials, decides on all matters not under other officials' specific jurisdiction, and enforces penalties. The referee indicates when the ball is dead or out of play, and when it may again be put into play. The referee uses hand signals to indicate these specific decisions and penalties. The referee also makes all final decisions regarding instant replay, when a questionable call is reviewed on videotape.

The umpire makes decisions on questions concerning the players' equipment, their conduct, and their positioning. The principal duty of the linesman is to mark the position of the ball at the end of each play. The linesman has assistants who measure distances gained or lost, using a device consisting of two vertical markers connected by a chain or cord 10 yd (9 m) long. The linesman must also watch for violations of the rule requiring players to remain in certain positions before the ball is put into play. The field judge times the game, using a stopwatch for this purpose. In some cases, the stadium scoreboard has a clock that is considered official.

A football is an extended spheroid with a circumference of 28.5 in (72.4 cm) around the long axis and 21.25 in (54 cm) around the short axis. It weighs between 14 and 15 oz (397 and 425 g). Most balls are tan-colored and have a white ring around each end. These rings help receivers and other players see the ball and its rotation during passing plays. The football also has eight stitches that protrude from one side. They help quarterbacks and other players grip the ball when throwing a pass or running with the ball.

Each football player wears a uniform that includes a numbered jersey. Beneath the jersey and pants each player also wears a set of gear collectively known as pads. The pads protect the player from bodily contact that may occur during the game. Most pads are made of lightweight foam and hard plastic shells that cover the thighs, hips, shoulders, and knees. On grass fields players wear spiked shoes, called cleats, which provide traction. On Astroturf, players usually wear shoes specially designed to grip the playing field and absorb the shock of the hard surface.

Every player wears a helmet to protect the face, head, and ears. The helmet consists of a durable plastic shell and a set of foam pads that cushion the head. A plastic strap attaches to each side of the helmet below the ears and runs underneath the player's chin. This strap keeps the helmet in place when the player is hit. The helmet also has holes near each ear to allow the player to hear. On the front of each helmet is a plastic-coated piece of metal called a facemask, which protects the player but also allows him to see. Lineman and linebackers usually have larger and more extensive facemasks because they do the majority of blocking and tackling. Backs and secondary players usually have more open facemasks that provide a wider field of vision. It is illegal during any point of the game to grab an opponent's facemask.

A regulation football game is divided into four quarters, each consisting of 15 minutes of playing time. The first two periods constitute the first half of a game; the second two make up the second half. Between the halves, a rest period, usually lasting about 15 minutes, is permitted. The teams change halves of the field at the end of each quarter. The clocks stop at the end of each quarter and at certain other times, when particular events occur or when designated by the officials.

At the beginning of each game, the referee tosses a coin in the presence of the two team captains to determine which team kicks off and which receives the kickoff. At the start of the second half, the team that kicked off in the first half receives the kickoff.

During an NFL regulation game the kickoff is made from the kicking team's 30-yard line. (During a college game the ball is kicked from the 35-yard line.) The kicking team lines up at or behind the ball, while the opponents spread out over their territory in a formation calculated to help them to catch the ball and run it back effectively. If the kick stays within the boundaries of the field, any player on the receiving team may catch the ball, or pick it up on a bounce, and run with it. As the player runs, the player may be tackled by any opponent and stopped; this is known as being downed. The player carrying the ball is considered downed when one knee touches the ground. Tacklers use their hands and arms to stop opponents and throw them to the ground. After the ball carrier is stopped, the referee blows a whistle to stop play and places the ball on the spot where the runner was downed. Play also stops when the ball carrier runs out of bounds.

The T-formation

The T-formation is one of football's basic and most versatile offensive formations. In this formation, the tackles, guards, and center align to protect the quarterback, while the ends line up on the outside to block or receive a pass. The halfbacks and fullback line up behind the quarterback in preparation for a possible handoff.

Offensive plays in football are run from a set formation known as a scrimmage. Before a scrimmage begins, the team on offense usually gathers in a circle, called a huddle, and discusses the play it will use. A coach either signals the play choice to the team from the sidelines, sends a play in with a player, or the team's quarterback chooses from among the dozens of preset plays that the team has prepared. The defensive team also forms a huddle and discusses its next attempt to slow the offense. Each play is designated by code numbers or words, called signals. After the teams come out of their respective huddles, they line up opposite each other on the line of scrimmage. If the quarterback analyzes the defensive alignment and decides that the chosen play should be changed, the quarterback can call an audible and shout the coded directions for a new play. The defense can adjust its formation at this point as well.

Play begins when the center crouches over the ball and, on a spoken signal, hikes it to the quarterback. Based upon the chosen play, the quarterback can pass the ball, hand it off to a teammate, or run with it. During the scrimmage, the players on the offensive team may block the defenders using their bodies, but they are constrained by specific rules regarding the use of their hands or arms. The player running with the ball, however, is allowed to use an arm to push off potential tacklers.

Perhaps the most exciting offensive play is the forward pass, in which the ball is thrown downfield. The quarterback nearly always throws the ball, and backs, ends, and wide receivers may catch it. A forward pass may be made only during scrimmage, and then only from behind the line of scrimmage. A lateral pass (throwing the ball backwards or on a line parallel to the line of scrimmage) may be made anywhere on the field to anyone anytime the ball is in play.

Standard Defensive Formations

In the three-four defense the positioning of four linebackers provides extra coverage of possible pass receivers. This defense is frequently used when a pass is expected. Another standard scheme is the four-three defense. The use of four linemen (ends and tackles), three linebackers, and four defensive backs (cornerbacks and safeties) creates a balanced defense capable of stopping either the rush or the pass.

The defending team tries to keep the offense from advancing the ball, or to stop the offense for a loss by tackling the ball carrier before the ball carrier reaches the line of scrimmage. The offense must advance the ball at least 10 yards in four tries, called downs. After each play, the teams huddle and then line up again and a new scrimmage takes place. If the team on offense fails to travel 10 yards in four downs, it must surrender the ball to its opponent after the fourth down.

A team will often punt on fourth down if it has not gained at least 10 yards in its previous three tries. In punting, the punter receives the snap, drops the ball, and kicks it before it touches the ground. By punting, a team can send the ball away from its own end zone before surrendering possession of it, thus weakening the opponent's field position.

The defense can also gain possession of the ball by recovering a fumble or making an interception. A fumble occurs when a player in possession of the ball drops it before being tackled and downed. Other players can then fall on top of or pick up the loose ball. An interception occurs when one of the defensive players catches a ball thrown by the offensive team. The defensive player who gains a fumble or interception may run with the ball toward the opponent's end zone until being tackled and downed or forced out of bounds.

The object of the game is to score more points than the opposing team. A team scores a touchdown when one of its players carries the ball into the opposing team's end zone or catches a pass in the end zone. A touchdown is worth six points. After a team has scored a touchdown, it tries for an extra-point conversion. This is an opportunity to score an additional one or two points. In college football the offensive team lines up at the opponent's three-yard line and runs, passes, or kicks the ball. A running or passing conversion in which the ball crosses the goal line counts for two points. A kick, in which one player receives the snap and holds the ball upright on the ground for a teammate to kick between the goalposts and over the crossbar, counts for one point. In professional football, the offensive team lines up two yards from the goal line during an extra-point conversion. Just as in the college game, one or two points may be scored depending on the conversion method used.

On offense, teams may also attempt to score by kicking a field goal, which counts for three points. For a successful field goal, the ball must be kicked between the goalposts and over the crossbar. Teams usually try for a field goal when they have the ball on the fourth down and are within about 35 yards of the end zone. After each field goal and extra-point conversion, the scoring team must kick off to its opponents.

Two points are awarded to the defensive team for making a safety. A safety occurs when a play ends and the offensive team has possession of the ball behind its own goal line. When the offensive team suffers a safety, it must punt the ball to the opponents to restart play. In certain situations, such as after receiving a kickoff, the offensive team is permitted to down the ball behind its line intentionally. This play, called a touchback, does not count in the scoring. Instead the ball is moved to the receiving team's 20-yard line, where the offensive team puts the ball back in play.

In college football, a game that ends in a tie is decided by a tiebreaker played in an overtime period. One team begins an offensive series on the opponent's 25-yard line. The team's possession ends when it scores, turns the ball over, or fails to convert a fourth-down play. The other team then receives the same chance to score. The team that is leading at the end of the overtime period wins the game. Additional overtime periods can be played if the teams fail to break the tie. In case of a tie in an exhibition or regular-season professional game, the teams play an overtime period, known as sudden death, in which the first team to score is declared the winner. If neither team has scored at the end of this 15-minute overtime period, then the tie is allowed to stand. In professional playoff games no ties are allowed, and the teams play until one scores.

Each year more than 20 million people play some form of amateur football. Levels include programs for young boys and girls, junior high and high school competition, college intramural and intercollegiate play, and informal adult leagues. Intercollegiate contests are attended by more than 35 million spectators each year. Most organized amateur play takes place from September through January.

More than 1 million high school athletes play football in the United States. The majority of these athletes are boys; however, some girls also participate in the sport. The National Federation of State High School Associations (NFHS), located in Indianapolis, Indiana, governs high school football. The NFHS does not crown a national champion. Instead, high school teams compete to win their state championship, with each state having its own guidelines for determining titles. Most states have several state champions, each in a category determined by school size. The most talented high school players may receive scholarships to attend and play football in college.

Football is one of the most popular college sports in the United States. The National Collegiate Athletic Association (NCAA), located in Indianapolis, is the most important organization governing major college competition. The National Association of Intercollegiate Athletics (NAIA), located in Tulsa, Oklahoma, oversees competition for smaller four-year schools. The National Junior College Athletic Association (NJCAA), located in Colorado Springs, Colorado, governs play for two-year and community colleges throughout the country. Under the jurisdiction of these national governing bodies are individual conferences and leagues based on school size and regional location. Well-known NCAA conferences include the Atlantic Coast, the Big Ten (northern Midwest), the Big 12 (Midwest), the Pacific-10 (Western states), the Southeastern Conference, and the Ivy League (Northeast). Many university stadiums hold more than 50,000 spectators; a few hold more than 100,000.

Some of the most accomplished players in college football history include Jim Thorpe of the Carlisle Indian School; George Gipp of the University of Notre Dame; Red Grange of the University of Illinois; Tom Harmon of the University of Michigan; Doak Walker of Southern Methodist University; Glenn Davis and Doc Blanchard, the so-called Touchdown Twins of Army (the U.S. Military Academy); Joe Namath of the University of Alabama; Walter Payton of Jackson State University; Tony Dorsett of the University of Pittsburgh; Joe Montana of the University of Notre Dame; Marcus Allen of the University of Southern California; Jerry Rice of Mississippi Valley State University; and Bo Jackson of Auburn University.

After each college season, the Downtown Athletic Club of New York City presents the Heisman Trophy to the top college football player in the United States. Four players are nominated for the award, and a poll of sportswriters determines the winner. The award is named after John William Heisman, an outstanding early college football coach who is credited with several modern innovations, such as the center-quarterback snap and the forward pass. The trophy was first awarded in 1935, and although any position player can win it, the Heisman winner is usually a quarterback, running back, or wide receiver. Winners of the Heisman Trophy who went on to excel in professional football include Paul Hornung, Roger Staubach, Earl Campbell, and Barry Sanders.

Several other awards are given to the nation's best player at specific positions. These include the Outland Trophy and Lombardi Award for the best lineman, the Butkus Award for the best linebacker, and the Thorpe Award for the best defensive back.

College teams generally play 11 or 12 games during the fall. The best college teams are awarded trips to so-called bowl games, which match outstanding teams in specially arranged contests. The tradition began in 1902 at Pasadena, California, when Stanford University invited the University of Michigan to come to California for a New Year's Day contest. This event soon became the celebrated Rose Bowl game. Today, hundreds of thousands of fans travel to bowl games to watch their favorite teams play. In addition to the Rose Bowl, notable bowl games include the Cotton Bowl in Dallas, Texas; the Fiesta Bowl in Phoenix, Arizona; the Orange Bowl in Miami, Florida; and the Sugar Bowl in New Orleans, Louisiana. Major corporations now sponsor many of the bowls.

The top division of college football remains the only level of NCAA sport that does not have a national championship tournament. The lucrative bowl system has been the biggest impediment to adopting a championship tournament like those held for lower-division NCAA football. Before the 1998 college season, the champion college team was selected by national polls of coaches and sportswriters. During some years, several teams posted similar win-loss records, causing debates over which team should be crowned the national champion. In 1998 the Bowl Championship Series (BCS) was instituted to determine the Division I national champion.

During the season the BCS ranks each team using a complex system. The system takes into account four factors: the team's win-loss record; the strength of its scheduled opponents; polls of coaches and sportswriters; and a ranking derived by combining and comparing several different computerized rankings. Based on the BCS regular-season ranking, teams are invited to play in various bowl games. The top two teams play in the BCS championship game, which rotates each year among the Fiesta, Sugar, Orange, and Rose Bowls. The winner of this game is crowned the national champion.

The major professional league in the world is the National Football League (NFL). Over the years, however, several other leagues have formed in North America and Europe, playing regulation football or a modified version of the sport.

The NFL consists of 31 teams that are divided into two conferences: the American Football Conference (AFC) and the National Football Conference (NFC), each of which has three divisions. The NFL season is played during the late summer, through autumn, and into January. Professional teams play 4 exhibition games, followed by 16 regular-season games. Teams play one game each week, using the time between games to recover, practice, and prepare for the next game. Each team receives one week without a game, known as a bye, during the season.

At the end of the regular season, each conference holds separate playoff games to determine the conference champion. The top team in each division automatically qualifies for the conference playoffs and is ranked number one through three based on its win-loss record. Three additional teams, called wild cards, also qualify for playoff berths based on their win-loss record in the conference. During the first round of the playoffs, the lowest-ranked wild-card team plays the lowest-ranked division champion, while the other two wild-card teams play each other. The losers are eliminated and the winner of each game advances to play one of the remaining division champions in the semifinals. Semifinal winners advance to the conference finals, and the winner of that game is declared the conference champion.

The Super Bowl is the final contest of the NFL's season. Held each January, it pits the AFC and NFC champions against each other. The Super Bowl reaches hundreds of millions of viewers around the world. The first Super Bowl took place in 1967, when there were actually two separate football leagues, the NFL and the American Football League (AFL). In this game, the Green Bay Packers of the NFL defeated the Kansas City Chiefs of the AFL in what was called the AFL-NFL World Championship Game. The game was renamed the Super Bowl in 1969.

Every April the NFL conducts its amateur draft, in which each team obtains the rights to the professional services of the best college players. Any player who is three seasons out of high school qualifies for the NFL draft if that player renounces college football eligibility by early January. To determine the draft order the NFL goes by the win-loss records of the previous season, so that teams with poorer records draft earlier than those with better records. The NFL draft consists of seven rounds. Those players not selected in the draft can be invited to try out for a team and are sometimes signed to contracts as free agents.

The NFL is a big business for players, owners, advertisers, and other industries tied to the sport. NFL franchises generate huge revenues for host cities, in addition to promoting civic pride and national exposure. Thus, cities often compete for teams, offering prospective teams bigger and better stadiums, guaranteed fan support, and various economic incentives. In the 1980s three NFL teams relocated: the Oakland Raiders moved from Oakland, California, to Los Angeles in 1982; the Colts moved from Baltimore, Maryland, to Indianapolis, Indiana, and became the Indianapolis Colts in 1984; and the Cardinals moved from St. Louis, Missouri, to Phoenix, Arizona, and became the Phoenix Cardinals in 1988 (later changed to Arizona Cardinals). Several other moves occurred in the 1990s. In 1995 the Los Angeles Rams became the St. Louis Rams when they moved from Los Angeles to St. Louis, and the Raiders returned to Oakland. The Cleveland Browns moved to Baltimore, Maryland, in 1996; the team was renamed the Baltimore Ravens. In 1997 the Houston Oilers moved to Tennessee and became the Tennessee Titans. Other teams have agreed to stay in their home cities only with the promise of new facilities.

New teams are periodically accepted into the NFL, and there is usually fierce competition among cities to be selected as the home for a new team. In 1995 two of these expansion teams began play: the Carolina Panthers, in Charlotte, North Carolina; and the Jacksonville Jaguars, in Jacksonville, Florida. A new Cleveland Browns franchise began play in 1999. The next expansion was scheduled for 2002, when the Houston Texans will begin play.

Arena Football

Inspired by indoor soccer, the Arena Football League (AFL) began play in 1987 and has steadily expanded. A smaller field and rules that are different from standard American football make the game high-scoring and fast-paced. In this game, the Los Angeles Avengers defeated the Carolina Cobras, 58-50.

Besides the NFL, other early professional football leagues in North America included the Canadian Football League (see Football, Canadian); the All-America Football Conference (AAFC), which played from 1946 to 1949; and the American Football League (AFL), which played from 1960 to 1969. The AAFC and the AFL ceased to exist when they merged with the NFL. From 1983 to 1985 the United States Football League (USFL) tried to compete with the NFL by playing in the spring and summer, but it folded after the 1985 campaign.

In 1991 the World League of American Football was formed with the intention of fostering interest in American football and the NFL in Europe. The league had teams in European and North American cities, but suspended play after the 1992 season. It restarted in 1995 as NFL Europe, with teams only from European cities. NFL Europe has proved to be an effective training ground for prospective NFL players, offering valuable playing time that NFL teams cannot provide.

In the late 1990s the Arena Football League gained increased popularity. The league, which began play in 1987, features high-scoring indoor football on a field half the length of an NFL field, with teams of eight players each. There are several other major differences between arena football and regulation NFL football. For example, punting is not allowed-on fourth down teams must go for a first down, a touchdown, or a field goal. Also, the fields have nets set up beyond both end zones. The defensive team can play a missed field goal off the net, and the receiving team on a kickoff can do the same. In addition, a forward pass that bounces off the net is in play until it hits the ground. In the year 2000, the popularity of arena football led to the formation of Arena Football 2, an expansion league. In early 2001 a new NFL rival, the Extreme Football League (XFL), began play. This league used different rules to make the game faster paced and more exciting, but poor television ratings caused it to fold after one season.

The forerunner of American football may have been a game played by the ancient Greeks, called harpaston. In this game there was no limit to the number of players. The object was to move a ball across a goal line by kicking it, throwing it, or running with it. Classical literature contains detailed accounts of the game, including its rougher elements, such as ferocious tackling.

Most modern versions of football originated in England, where a form of the game was known in the 12th century. In subsequent centuries football became so popular that various English monarchs, including Edward II and Henry VI, forbade the game because it took interest away from the military sport of archery. By the middle of the 19th century, football had split into two distinct entities. Still popular today, these two sports were soccer and rugby. American football evolved from these two sports. The sport called soccer in the United States is still known as football throughout much of the world.

Most football historians agree that the first organized football game took place on November 6, 1869, when teams from Rutgers and Princeton universities met in New Brunswick, New Jersey. In the early games, each team used 25 players at a time. By 1873 the number was reduced to 20 players, and by 1876 it was further reduced to 15 players. In 1880 Yale coach Walter Camp set the number at 11 players. He also created the quarterback position and the system of downs.

In the early 1900s college football games were popular sports spectacles, but the professional game attracted limited public support. College games were extremely rough, and many injuries and some deaths occurred. Educators considered dropping the sport despite its popularity on campuses, and United States president Theodore Roosevelt, an ardent advocate of strenuous sports, declared that the game must be made safer. As a result, football authorities revamped the game, and many of the rougher tactics were outlawed.

College coaches such as Amos Alonzo Stagg, Pop Warner, Bob Zuppke, and Knute Rockne developed many of the early offensive techniques and play formations. Following very few historical precedents, these men invented unique strategies that changed the nature of football forever.

Stagg was instrumental in developing the between-the-legs snap from center to quarterback, the player in motion in the backfield before the snap of the ball, the onsides kick, the early T-formation, and many other innovations. In 1906 Warner unbalanced his line, placing four players on one side of the center and two on the other side, while shifting the backfield into a wing formation. The quarterback functioned as a blocker, set close behind the line and a yard wide of the center. At the same depth, but outside the line, was the wingback. Deep in the backfield was the tailback, who received most of the snaps, and in front and to the side was the fullback. This formation became known as the single-wing, and it remained football's basic formation until the 1940s.

Coach Zuppke ran single- and double-wing formations at the University of Illinois, often sending four or five receivers downfield in pass patterns. At Notre Dame in 1923 and 1924, Rockne instituted his famous Four Horsemen offense. Rockne set up the backs in a four-square, box alignment on one side. Then, in what was called the Notre Dame Shift, the backs would shift out of the box and into a single or double wing.

The first professional football game in the United States took place in 1895 in the town of Latrobe, Pennsylvania, between a team representing Latrobe and a team from Jeannette, Pennsylvania. In the following years many professional teams were formed, including the Duquesnes of Pittsburgh, Pennsylvania; the Olympics of McKeesport, Pennsylvania; the Bulldogs of Canton, Ohio; and the team of Massillon, Ohio. Noted college players who took up the professional game during its early years include Willie Heston (formerly at the University of Michigan), Fritz Pollard (Brown University), and Jim Thorpe (Carlisle Indian School).

The first league of professional football teams was the American Professional Football Association, formed in 1920. The admission fee was $100 per team. The teams pledged not to use any student player who still had college eligibility left, as the goodwill of the colleges was believed to be essential to the survival of the professional league. Thorpe, a player-coach for one of the teams, became president of the league during its first year.

The American Professional Football Association gave way in 1922 to the NFL. Red Grange, the famous halfback from the University of Illinois, provided a tremendous stimulus for the league when he joined the Chicago Bears in 1925 and toured the United States that year and the next. His exciting play drew large crowds. Thereafter, professional football attracted larger numbers of first-rate college players, and the increased patronage made the league economically viable.

Strategically, the early NFL game was hardly distinguishable from college football of the time. There was no attempt to break away from college playbooks or rulebooks, and for several years the NFL followed the NCAA Rules Committee recommendations. In the league's early years, players considered the low-paying NFL a part-time job and held other jobs during the day. Thus, while college coaches could drill their players daily for hours, professional football coaches arranged practices in the evenings, sometimes only three or four times a week.

The popularity of the professional game slowly began to equal its college rival after the NFL instituted its first player draft in 1936. As many talented college players opted to play in the NFL, the professional game also drew more fans. The Chicago Bears, the Chicago Cardinals, the Detroit Lions, the Green Bay Packers, and the New York Giants were some of the league's dominant teams during the period. Outstanding players included running back Cliff Battles, quarterback Sammy Baugh, running back Tony Canadeo, and receiver Don Hutson. The Great Depression of the 1930s and World War II (1939-1945), however, drained many of the early professional franchises of money and players.

After World War II, college teams were allowed free substitution of players-that is, a player could enter and leave the game an unlimited number of times, as long as the ball was not in play during the substitution. This feature of the game led to the modern two-platoon system, in which one group of 11 players enters the game to play offense and a second group enters to play defense. The trend toward platoons crossed over to the professional game.

In 1946 the All-America Football Conference (AAFC) was established as a rival to the NFL. The new league included the New York Yankees, the San Francisco 49ers, the Baltimore Colts (now Indianapolis Colts), and the Los Angeles Dons. The most powerful team in the new league was the Cleveland Browns, coached by football innovator Paul Brown.

Although talented, the quarterbacks of the 1930s and early 1940s seldom completed more than 50 percent of their passes. A major cause of these low percentages was the primitive nature of pass-blocking strategies. With little protection, passers always had to throw while avoiding incoming rushers. Brown installed a blocking system that radically transformed the passing game. He changed the system by arranging the linemen in the form of a cup that pushed most pass-rushers to the outside and provided a safe area, called a pocket, from which the quarterback could pass. Using the strategy, Brown coached Cleveland to four AAFC championships from 1946 to 1949.

In 1950 the Browns, 49ers, and Colts joined the NFL in a merger of the two leagues. The move ushered in a period of popularity and prosperity. Throughout the 1950s and early 1960s players such as quarterbacks Norm Van Brocklin, Y. A. Tittle, and Johnny Unitas; receiver Tom Fears; running back Jim Brown; defensive back Tom Landry; linebacker Ray Nitschke; and all-around standout Frank Gifford ignited the league and attracted fans. During the period a select group of franchises won NFL championships, including Cleveland (1950, 1954, 1955), Detroit (1952, 1953, 1957), and Baltimore (1958, 1959). The advent of television helped to popularize the professional game when in 1956 the Columbia Broadcasting System (CBS) began to broadcast select games.

In 1960 the Packers reached the NFL championship game but lost to the Philadelphia Eagles. Nevertheless, the game signaled the rise of the Green Bay franchise under head coach Vince Lombardi. An intimidating and motivating individual, Lombardi led Green Bay to the NFL title the following year and added two more NFL championships in 1962 and 1965.

Seeing that a profit could be made from professional football, Texas businessman Lamar Hunt formed the American Football League (AFL) in 1960 as a rival to the NFL. Teams in the new league included the Houston Oilers, the Kansas City Chiefs, the Oakland Raiders, and the New York Jets. The two leagues fought bitterly for players, media attention, and profits. Standouts in the new league such as Jack Kemp, Lance Alworth, and Joe Namath helped the AFL establish itself on par with the NFL.

In 1966 the two leagues agreed on a merger plan. The first AFL-NFL World Championship Game, featuring the AFL-champion Chiefs and the NFL-champion Packers, was played in January 1967. The Packers won the contest, later renamed Super Bowl I, 35-10. In 1968 the Packers defeated the AFL's Oakland Raiders in Super Bowl II, but the game validated the AFL's talent. In 1969 the AFL's Jets defeated the Colts in a huge upset in Super Bowl III. In 1970, the leagues merged into two 13-team conferences under the NFL name. The Browns, Colts, and Pittsburgh Steelers joined the 10 AFL teams to form the AFC, and the remaining NFL teams formed the NFC.

During the early 1970s offensive play suffered as result of complex defensive strategies. Three coaches in particular, Tom Landry of the Dallas Cowboys, Chuck Noll of the Steelers, and Don Shula of the Miami Dolphins, created defensive tactics that closed passing lanes and forced offenses to rely on running the ball. The shift resulted in defensive units with names such as the Doomsday Defense of the Cowboys, the Steelers' Steel Curtain, the Minnesota Vikings' Purple People Eaters, and the Los Angeles Rams' Fearsome Foursome. In 1972 Miami's unheralded defense teamed with a celebrated offense led by quarterbacks Bob Griese and Earl Morrall, and the Dolphins compiled a record of 14 wins and 0 losses-becoming the only team to finish a NFL regular season undefeated. Following their perfect season Miami won Super Bowl VII.

In an attempt to maintain public interest in the game during the early 1970s, NFL administrators brought the hash marks in closer to the center of the field to give offenses more room to throw wide passes. The move, which increased scoring and made the game more exciting, also helped bolster the running game. In 1972 ten NFL runners gained more than 1,000 yards in one season for the first time in history. During the next season, Buffalo Bills running back O. J. Simpson rushed for more than 2,000 yards, the first time a player had gained that many yards in a single season.

Quarterbacks such as the Cowboys' Roger Staubach and the Steelers' Terry Bradshaw quickly developed playing styles that took advantage of the openness of the field created by the rule change. Both quarterbacks developed aggressive passing attacks that depended on pinpoint accuracy. During the mid- to late 1970s and early 1980s, an intense rivalry between Dallas and Pittsburgh drew fans to the game. Pittsburgh won four Super Bowls (1975, 1976, 1979, 1980), while Dallas won in 1978. The Steelers' 1979 victory over the Cowboys in Super Bowl XIII is considered one of the most memorable games in the sport's history.

Television continued to play a role in the popularization of the game, and in 1970 the American Broadcasting Company (ABC) created Monday Night Football, hosted by former quarterback Don Meredith and commentators Keith Jackson and Howard Cosell. After one season former NFL player Frank Gifford replaced Jackson. Each week during the regular season the show featured a popular match-up. It was an instant success and became one of television's longest-running sports programs. After Meredith and Cosell retired, a number of former NFL players served as announcers on the show, including Dan Dierdorf, Fran Tarkenton, O. J. Simpson, and Lynn Swann.

The San Francisco 49ers were the dominant team of the 1980s, as quarterback Joe Montana keyed the team to four Super Bowl victories (1982, 1985, 1989, 1990). Montana, who benefited from good blocking protection, read defenses well and could pass while scrambling away from tacklers. His favorite receiver was Jerry Rice, who eventually became the NFL career leader in career touchdowns. Other powerful teams during the 1980s included the Chicago Bears, the Washington Redskins, and the Raiders, who moved from Oakland to Los Angeles after the 1981 season, and back to Oakland after the 1994 season.

In the mid-1980s a new type of defensive player emerged. While speedy defensive backs covered equally fast wide receivers, a player called the rush-linebacker emerged with one specialized duty: pressuring the quarterback. With no pass-coverage responsibilities, the fast and strong rush-linebacker focused his attention on the quarterback and the running backs. The New York Giants' Lawrence Taylor, perhaps the best player of all time at this position, led New York to a Super Bowl victory in 1987.

The late 1980s saw players pushing to improve their labor situation. In 1989 the threat of a lawsuit caused the NFL to change its original policy and allow college underclassmen to enter the draft. Juniors and third-year sophomores are now eligible, and many college stars turn professional before exhausting their college eligibility.

Free agency emerged in 1992 in a settlement of a lawsuit filed in 1987 by the NFL Players Association. The association was formed in 1956 when players began to demand improved conditions. The union brought the suit in 1987 on behalf of players seeking freedom of movement between teams. The NFL's Management Council initially objected to any form of free agency, so in 1987 veteran players held a three-game strike in protest. Now in place, free agency is accompanied by a salary cap that limits teams to a maximum annual player payroll.

In the early 1990s quarterback Jim Kelly and running back Thurman Thomas led the Buffalo Bills to four consecutive Super Bowl appearances (1991-1994). However, they lost them all. Dallas returned to the Super Bowl in 1993 behind running back Emmitt Smith and quarterback Troy Aikman. The pair led the Cowboys to Super Bowl victories that year and in 1994 and 1996.

Perhaps the greatest offensive players of the 1990s were running back Barry Sanders of the Lions and quarterbacks Steve Young of the 49ers, Dan Marino of the Dolphins, and John Elway of the Denver Broncos. Sanders led the NFL in rushing several times and became the first running back to rush for more than 1,000 yards in ten consecutive seasons (1989-1998). Young led the NFC in passing during five seasons (1991-1994 and 1996) and led the 49ers to a Super Bowl victory in 1995. Marino became the NFL's all-time passing leader by passing for 61,361 yards and 420 touchdowns. Elway led the Broncos to five Super Bowl appearances between 1987 and 1999, winning in 1998 and 1999. All of these players retired at the end of the decade.

The 2000 and 2001 Super Bowls ushered in a new era for the NFL, as the St. Louis Rams defeated the Tennessee Titans and the Baltimore Ravens beat the New York Giants for each franchise's first Super Bowl title. New stars such as quarterbacks Peyton Manning of the Colts and Dante Culpepper of the Vikings, defensive players Jevon Kearse of the Titans and Ray Lewis of the Ravens, running backs Eddie George of the Titans and Edgerrin James of the Colts, and receivers Rod Smith of the Broncos and Isaac Bruce of the Rams may be the leaders of the next generation to carve an NFL legacy.