Football is a game played by two opposing teams composed of eleven players each, on a rectangular field made of natural grass or artificial turf. An inflated leather ball, which is called a “football”(or simply “the ball”), is used by players to score points—with the winning team posting the most points after a game is completed.


The object of the game is to score points by carrying or passing the ball across the opponent's goal line or by kicking the ball through their goal posts (which is positioned just past their goal line within their end zone). When a player runs the ball over the goal line or catches the ball after it is passed into the end zone, then six points are scored. After a touchdown is accomplished, the scoring team has the opportunity to score one or two extra points by kicking the ball through the goal posts, or running or passing the ball into the end zone, respectively.

If a touchdown is not attempted, but instead a player tries to kick the ball through the goal post at the end of their drive, then three points are scored for a successful try. After such a possession, the team previously playing defense is awarded the ball for the next series of plays, and they become the offensive team, trying to race across their opposition's goal line at the opposite end of the field. The winning team will have scored more points than the losing team after the completion of four quarters of play.


Anyone can play the game of football in the backyard or at a local sports field. Sometimes it is called tackle football, while other times it is called touch or flag football. In each case, the purpose of the game is the same. Primarily, organized teams of football players consist of males, either boys or men. Many boys play football in organized leagues formed under the organization of the American Youth Football. They play under such league names as tiny mite, pee wee, and midget. As they grow older, thousands of young men participate on high school and college teams. They are each considered amateur football players because they do not play for money or other types of compensation. After the college football season ends, several bowl games are played to decide the best teams in various conferences around the country. Watching all levels of football is popular in the United States.

When men play football for money, they are playing professional football. The highest quality of professional football played in the country is within the National Football League (NFL). The ultimate goal of members of the NFL is to play in the Super Bowl at the end of the regularly scheduled season. Millions of spectators, both at the stadium and in homes and sports bars around the country, watch the contest in early February of each year.


Two football teams take their positions as they prepare for the center to snap the ball. American football is one of the most popular sports in the United States, with the annual Super Bowl being the most-watched sporting event in the country.

Two football teams take their positions as they prepare for the center to snap the ball. American football is one of the most popular sports in the United States, with the annual Super Bowl being the most-watched sporting event in the country.
(© Mary Katherine Wynn/

Modern American football was primarily based on a rugby-style of running game played with Rugby Football Union rules, rather than by the FA kicking style. The first football game played under modern American football rules was a game between McGill University (Montreal, Canada) and Harvard University (Cambridge, Massachusetts) in 1874.

Six years later, in 1880, football coach and sports writer Walter Camp (1859–1925), then a coach with Yale University, made some major changes to American football. Camp wanted the game to be distinct from rugby football. Therefore, he included such features as scrimmages, snap-back from center, and a system of downs, along with offensive and defensive lines and a backfield including the positions of quarterback, halfback, and fullback. His changes produced what is today called the game of American football and, consequently, Camp is commonly called “The Father of American Football.”


Walter Chauncey Camp was born in New Britain, Connecticut, in 1859, prepared for college at the Hopkins Grammar School, New Haven, and graduated from Yale in the class of 1880. For two years he attended Yale Medical School, where he gained a knowledge of anatomy and physiology. which he was later to employ in his training of youth. During his student days he engaged enthusiastically in all outdoor sports, but specialized in football which he played for six years. Upon leaving the medical school he took a subordinate position with the Manhattan Watch Company, New York and in 1883 became connected with the New York office of the New Haven Clock Company, a firm with which he was associated for the remainder of his life.

His business connections brought him to New Haven to live in 1888, and he soon became general athletic director and head advisory football coach at Yale. While a representative of the college at a rules conference, he had suggested modifications that revolutionized the game. The “scrimmage” was substituted for the “scrum”(the ball being put into play by one side instead of being left to a free–for–all scramble), the number of players was reduced from fifteen to eleven, and the key position of quarterback was created. His influence on the game, thus early begun, now continued for nearly 30 years. He is credited with the suggestions that led to the “fourth down rule” with the accompanying “gridiron” pattern of the field, and for the permission of tackling below the waist. Team play was his great objective, and his strategic ability contributed much to the development of its technique. An even greater contribution came from his love of clean sportsmanship, which directly and indirectly he instilled into players on college fields and in school yards. He created a literature of the game in books, magazines, and newspapers. In 1889 he began his custom of selecting an “All–America Team,” membership on which was considered the highest football honor—a remarkable testimonial to public confidence in Camp's knowledge of the game and his impartial sportsmanship.

(ullstein bild/Getty Images)

(ullstein bild/Getty Images)


American football—which is known in the United States as simply football—is a game whose objective is to score points by advancing the “football” into the end zone being defended by the team's competitor. Specifically, it involves the offensive team moving the ball down the long-length of the field with the primary use of running and passing plays, but sometimes by kicking the ball—in order to score a touchdown or a field goal. At the same time, the defensive team tries to prevent the offensive team from scoring with the use of tackling and other such means. Many people play football around the United States and in other parts of the world as a way to keep fit and have fun. Others play it professionally, meaning they are paid to play the game they love. The professionally played sport is a full contact sport, and because of this it can cause injuries.

The football is shaped roughly as an extended spheroid with eight stitches on its surface. Its shape includes a long-axis circumference of 28.50 inches (72.39 centimeters) and a short-axis circumference of 21.25 inches (53.97 centimeters). The ball weighs between 14 and 15 ounces (397 and 425 grams). Points are scored by carrying the football while: (1) running over the opponent's goal line, (2) catching a pass that is thrown (usually by the quarterback) over the goal line and into the end zone, (3) kicking the ball through the other team's goal posts, or (4) tackling an opposing ball carrier in his team's own end zone.

The short dimension of the field is crossed by yard lines every 5.0 yards (4.57 meters). Each goal line is designated as “0,” with the adjacent ones designated as “10,” the next ones “20,” the next ones “30,” the next ones “40,” and the one middle one as “50.” Two vertical (T-shaped) goal posts are positioned at the back of each end zone. Centered on the back lines of the field, they are 18.5 feet (5.64 meters) apart, and have a horizontal crossbar connecting them at a height of 10.0 feet (3.05 meters) from the ground.

The game consists of four 15-minute quarters. Two teams of 11 players are on the playing field at any given time. Currently, the NFL limits the number of total uniformed players for each team at 53 members. Substitutions are allowed at any time during the game. Three groups are the major divisions of each team. They are the offensive team, the defense team, and the special team.

The offense consists of the:

The NFL rules state that at least seven players must line up on the line of scrimmage on every offensive play. The other players may line up anywhere behind the line. The exact number of running backs, wide receivers, and tight ends may differ on any given play. For example, if the team needs, say, a large number of yards on third down (in order to make a first down and continue their offensive drive down the field), it may use no running backs, one tight end, and four wide receivers so it has ample number of potential receivers for the quarterback's pass. On the other hand, if it needs only a few inches to make a first down, it may eliminate all of its wide receivers and use two running backs and two tight ends to make sure they can get a first down.

The defense consists of the:

The members of the defensive team are not required by football rules to be in any certain location before the ball is snapped to the quarterback (other than behind the line where the ball is positioned). They often defend their turf by being assigned individual offensive players or by playing a zone in order to defend a pre-determined section of field. For a good defensive team, they must defend their portion of the field from the onslaught planned by their opponent.

The special team members are the players that deal with kicking the ball and returning balls back after they are kicked from the opposition team. The participants of this team include the:


To be successful in the game of football, players need special equipment on the field and physical training and conditioning off the field. Both are needed in preparation for playing the game of football to make sure players stay healthy and fit.


Each player wears a standard team uniform (jersey and pants) to identify one team from the other team. Each uniform has a number on the back of the jersey. Lightweight foam and hard plastic shells compose the shoulder pads worn underneath the jersey to protect the player from injuries. Players also are required to wear pads to cover the hip and knees. Optional equipment include neck rolls, back pads, elbow pads, thigh pads, spider pads (a type of vest), rib protectors, elbow pads, and gloves. In cold weather, extra clothing is sometimes worn. Special shoes are used to help grip the surface of the field, which may be natural grass or artificial turf. Their shoes also help to absorb shocks as they run.

Helmets made of a plastic shell and foam pads must be worn by all players. They protect the face and ears, and cushion the head from impacts. Two holes on the helmet are positioned in front of the ears so the men can hear one another. A plastic-coated metal face mask, which is made of various shapes depending on the position being played, is worn on the front of the helmet. Players on the line have larger face masks for additional protection, while wide receivers have smaller ones to allow them to see better. A strap worn around the chin helps secure the helmet. It is illegal to make helmet-to-helmet contact during the game, and it is also illegal to grab a face mask during play. Penalties and fines can be issued by the game's referees or the NFL officials.

Training and conditioning

Football training and conditioning is essential for the playing of the game. The training during the offseason is the most important part of this training. The goal is to develop maximum fitness so that it peaks just before the start of the football season.

Some of the key parts of training and conditioning in football are maximal and functional strength training, power training and conditioning, and interval training, which all help to increase and maintain strength, power, endurance, and speed. For instance, functional strength training helps to correct any imbalances that occur during the training program. It usually is begun early in the training program so the player is prepared for more strenuous training later on.

A hypertrophy program is also part of training and conditioning. It is designed to increase muscle mass. Even though muscle mass is important, such training does not develop the strongest muscles. As such, hypertrophy training is only a small part of the entire strength training process. However, linemen will use such training more than other players due to their need for the most muscle mass in their strenuous roles of tackling and blocking on the field.

Early in preseason training, developing muscle mass and strength will take precedence over increasing speed and agility. Light aerobic exercise will be used after intense training sessions as an aid to muscle recovery. Later on in preseason workouts, after muscles have been built and power attained, intense interval training will help to increase speed and mobility on the football field. Quickness and agility, especially for the runners, should hit their peak just before the season begins.

During all phases of training and conditions, flexibility training is essential. The degree of range of movement that each player should have attained during training will have a dramatic effect on speed, agility, strength, and power while on the playing field. It will also minimize the risk of injuries. In addition, a daily schedule of stretching exercises should be performed as part of warm ups at the start of sessions and cool downs at their end.

During the season, all football players will keep training and conditioning to maintain their fitness levels. All of their sessions will be modified to accommodate their individual and team schedules. However, they will include aspects of those routines performed in the off-season.

Depending on the position being played in football, players need the following elements of their fitness training: maximum speed, acceleration, and agility (especially for the running backs and wide receivers), muscular endurance (such as, for the men on the line), and flexibility and mobility (for all football players). With a proper fitness schedule in the off-season, football players will be prepared for the dangers that lurk around every yard marker in the game of football.


Football injuries range from minor ones (such as aches and pains) to more serious traumatic ones (such as concussions and broken bones). Some of the most common injuries caused by playing football are head concussions; broken arms, legs, ankles, wrists, and noses; and sprains and tears to various muscles, tendons, and ligaments. Broken necks are a special concern with football players because they can end a career and sometimes paralyze the player for life. In addition, even mild brain trauma from several concussions during the career of a football player can lead to various disorders later in life, such as dementia. Dehydration and exhaustion can also occur while playing football.

Some of the more common injuries to the knee and leg include: groin pull; pulled, torn, or stained hamstring; various anterior and posterior cruciate ligament (ACL/PCL); pulled or strained calf muscle; and skin splints. Common injuries to the head, neck, and shoulder include: concussion; shoulder fracture, separation, or dislocation; whiplash or neck strain; and torn rotator cuff.

Concussions (traumatic brain injuries) in the NFL have come to the forefront of attention in professional football within the United States. In the past NFL seasons, medical personnel used standardized concussion assessment packages on the sidelines of each game to evaluate any person thought to have sustained a concussion while playing. The package includes a symptom checklist and a neurological examination, which includes a cognitive evaluation (e.g., are thoughts being processed correctly?) and a balance assessment (Can the player alternatively touch his nose with forefingers on his left and right hands?). The NFL requires football players who show concussion symptoms to sit out the rest of the game or practice and to be analyzed by an independent neurologist before returning to play.

Foot and ankle injuries frequently occur in football. Some of them include ankle sprain with stretching or tearing of the ligaments around the ankle joint; Achilles tendonitis or Achilles tendon rupture; turf toe; and blisters on the feet. Hand injuries include wrist sprains and tendinitis and finger fractures. The back can be exceptionally painful when it is injured in football. Such injuries include muscle strains, low back pain, herniated disks, and general backaches and stress.

Some risks in football are self-inflicted. The use of performance-enhancing drugs in the NFL has been a serious concern since the late 1980s. Performanceenhancing drugs include such drugs as anabolic steroids, human growth hormones, stimulants, painkillers, sedatives, and diuretics. In that decade, players began to be tested for steroid use and suspensions were made against offending players. In the 2010s, the NFL conducts random drug tests each year based on its banned substances policy. If a positive drug test is found, the offending player will be suspended without pay for four games for the first offense, eight games for the second offense, and twelve games for the third offense.

Achilles tendinitis—
An inflammation of the Achilles tendon that occurs with overuse of the affected limb (posterior leg).
An injury to the brain caused by a blow to the head, which causes temporary disorientation and other side effects.
The deterioration of cognitive functions, such as memory, while other intellectual functions remain normal, such as hearing and seeing.
Performance enhancing drugs—
Any type of drug used to increase performance, such as within an athletic event.
Turf toe—
A painful, red, swollen big toe that is caused by inflammation of the tendons within the toe's dorsal and plantar surfaces.
Wildcard team—
A term referring to a football team that is awarded a position within the NFL playoffs (based on its ratio of wins and loses) after not having won its division during the regular season.
An injury to the neck caused by a motion or force.

In addition, the National Collegiate Athletic Association (NCAA) has found that illegal drug use is also prevalent in college football, as it has been found in youth football activities, even at levels younger than high school.


See also Youth sports .




Gems, Gerald R., and Gertrud Pfister. Understanding American Sports. London: Routledge, 2009.

Moorman III, Claude T., and Donald T. Kirkendall, eds. Praeger Handbook of Sports Medicine and Athlete Health. Santa Barbara: Praeger, 2011.

Ramseyer, Bill. Winning Football. Champaign: Human Kinetics, 2011.

Stewart, Mark, and Mike Kennedy. Touchdown: The Power and Precision of Football's Perfect Play. Minneapolis: Millbrook Press, 2010.


American Youth Football and Cheer, Football@american

National Collegiate Athletic Association, 700 W Washington St., PO Box 6222, Indianapolis, IN, 46206-6222, USA, (317) 917-6222, Fax: (317) 917-6888, .

National Football League, 280 Park Ave., New York, NY, 10017, (212) 450-2000, .

William A. Atkins, B.B., B.S., M.B.A.

  This information is not a tool for self-diagnosis or a substitute for professional care.