American football resulted fromseveral major divergences fromrugby football, most notably therule changes instituted by WalterCamp, considered the "Father ofAmerican Football." Among theseimportant changes were theintroduction of the line ofscrimmage and of down-and-distance rules. Walter Camp
The origin of professional football can be traced back to 1892, with William “Pudge” $500 contract to play in a game for the Allegheny Athletic against the Pittsburgh Athletic Club. The first Professional "league" was the Ohio League, formed in 1903, and the first Professional Football championship game was between the Buffalo Prospects and the Canton Bulldogs in 1919. In 1920, the American Professional Football Association was formed. The first game was played in Dayton, Ohio on October 3, 1920 with the host Triangles defeating the Columbus Panhandles 14–0. The league changed its name to the National Football League (NFL) two years later, and eventually became the major league of American football. High school football dates to the 1880s and enjoys regional popularity.
Football is played on a field 360 by 160 feet (109.7 by 48.8 meters).The longer boundary lines are sidelines, while the shorter boundarylines are end lines. Sidelines and end lines are out of bounds.
Near each end of the field is a goal line; they are 100 yards(91.4 m) apart. A scoring area called an end zone extends 10yards (9.1 m) beyond each goal line to each end line. Theend zone includes the goal line but not the end line. Yardlines cross the field every 5 yards (4.6 m), and are numberedevery 10 yards from each goal line to the 50-yard line, ormidfield.
At the back of each endzone are two goalposts(also called uprights)connected by a crossbar10 feet (3.05 m) from theground. For high skilllevels, the posts are18 feet 6 inches (5.64 m)apart. For lower skilllevels, these are widenedto 23 feet 4 inches(7.11 m).
Each team has 11 players on the field at a time. Usually thereare many more players off the field. Teams may substitute forany or all of their players during the breaks between plays. Asa result, players have very specialized roles and are dividedinto three separate units: the offense, the defense and thespecial teams.
The game begins with a cointoss to determine which teamwill kick off to begin the gameand which goal each team willdefend.A standard football gameconsists of four 15-minutequarters with a half-timeintermission after the secondquarter. The clock is stoppedafter certain plays, therefore, agame can last considerablylonger.
The team that takes possession of the ball (the offense) hasfour attempts, called downs, in which to advance the ball atleast 10 yards toward their opponents (the defenses) endzone.
The ball is always put into play by a snap. Offensiveplayers line up facing defensive players at the lineof scrimmage. One offensive player, thecenter, then passes the ball backwards betweenhis legs to a teammate behind him, usually thequarterback.
Players can advance the ball in two ways: By running with the ball, also known as rushing. By throwing the ball to a teammate, known as a pass or as passing the football.
A down ends, and the ball becomes dead, after any of the following: The player with the ball is forced to the ground (a tackle) or has his forward progress halted by members of the other team (as determined by an official). A forward pass flies beyond the dimensions of the field (out of bounds) or touches the ground before it is caught. This is known as an incomplete pass. The ball or the player with the ball goes out of bounds. A team scores.
A touchdown (TD) is worth 6 points. It is scored when a player runs the ball into or catches a pass in his opponents end zone. A field goal (FG) is worth 3 points, and it is scored by kicking the ball through the goalposts def A safety, worth 2 points, is scored by the opposing team when the team in possession at the end of a down is responsible for the ball becoming dead behind its own goal line. For instance, a safety is scored by the defense if an offensive player is tackled, goes out of bounds, or fumbles the ball out of bounds in his own end zone. ended by the opposition.
In the United States, the major forms arehigh school football, college football andprofessional football.The highest level major professional leaguein the United States is the 32-team NationalFootball League (NFL).