American football, sometimes known as “gridiron,” is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. It is known simply as “football” in the United States and Canada. The defense, the team without the ball, seeks to halt the offensive’s movement and seize control of the ball for themselves. The offense, the team in possession of the oval-shaped football, strives to advance down the field by running with the ball or throwing it. The offense has four downs or plays to gain at least 10 yards; if they don’t, they lose the ball to the defense; if they do, they get another set of four downs to continue the drive.

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In order to score a touchdown or a field goal, the ball must be advanced into the end zone of the opposing team or kicked past their goal posts. At the conclusion of a game, the team with the most points wins.

In the United States, American football developed from the games of rugby and soccer. On November 6, 1869, two collegiate teams, Rutgers and Princeton, played the inaugural game of American football, utilizing regulations derived from soccer at the time. The snap, the line of scrimmage, eleven-player teams, and the idea of downs were all established through a sequence of rule modifications created from 1880 on by Walter Camp, known as the “Father of American Football.” Later rule modifications established the neutral zone, made the forward pass permissible, and outlined the football’s dimensions and form.

Although its rules were devised independently from those of Camp, the sport is strongly similar to Canadian football, which emerged concurrently with the American version. Canadian football shares the majority of characteristics with American football that set it apart from rugby and soccer. The two competitions are regarded as the main gridiron football subtypes.