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.
IIFIELD
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.
IIIPLAYERS
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.
AOffense
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.
BDefense
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.
CSpecial Teams 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.
IVOFFICIALS .
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.
