American football

American football, commonly known as gridiron football in the United States and Canada, is a team sport in which two teams of eleven players fight against each other on a rectangular field with goalposts at each end. It is played on a rectangular field with goalposts at either end. It is the offence's goal to advance down the field by running with or passing the football; as a team without possession of the ball, it is the defense's goal to prevent the offensive team from advancing down the field and to seize control of the football for themselves. Football is played on an oval-shaped field. The offensive must gain at least 10 yards on each of the first four downs or plays of the drive; if they fail to do so, they forfeit the ball to the defence; if they succeed, they are awarded a new set of four downs to finish the drive. To score points, the ball must be moved into the other team's end zone for a touchdown or kicked past the opponent's goalposts for a field goal, with the latter being the more common method. Upon the end of a game, the winning side is determined by the amount of points scored by each team.

American football developed in the United States as a result of the sports of soccer and rugby gaining popularity in the country. When Rutgers and Princeton competed in the first-ever American football game on November 6, 1869, the rules were based on those of soccer at that time. The game was the world's first football match, and it was the first of its kind in the world. The snap, the line of scrimmage, eleven-player teams, and the idea of downs were all created by Walter Camp, known as the "Father of American Football," in a series of rule modifications that went into effect in 1880. In later rule revisions, the forward pass was made permissible, the neutral zone was established, and the football's size and form were defined. Football in Canada is closely related to the American game, having developed in tandem with and at the same time as the American version (although their rules were developed independently from those of Camp). Canada's national football team possesses the majority of the characteristics that distinguish American football from rugby or soccer. In the world of gridiron football, these two sports are regarded the most important variations.

In the United States, American football is the most popular sport. In addition to professional and college football, high school and youth football are the two other major levels of competition in the sport. Every year in the United States, approximately 1.1 million high school athletes and 70,000 college athletes participate, according to data from 2012. According to the National Football League, which is the most popular American professional football league, its average attendance is the highest of any professional sports league in the world. The Super Bowl, the league's championship game, is one of the most viewed club sports events on the planet. The league generates about US$15 billion in revenue each year, making it the most lucrative sports league in the world by a large margin. Other professional leagues exist in other parts of the world, but the sport does not enjoy the same level of international popularity as other American sports such as baseball and basketball do.