American football (ball)

A football is a ball inflated with air that is used to play one of the various sports known as football. In these games, with some exceptions, goals or points are scored only when the ball enters one of two designated goal-scoring areas; football games involve the two teams each trying to move the ball in opposite directions along the field of play.

The first balls were made of natural materials, such as an inflated pig bladder, later put inside a leather cover, which has given rise to the American slang-term "pigskin". Modern balls are designed by teams of engineers to exacting specifications, with rubber or plastic bladders, and often with plastic covers. Various leagues and games use different balls, though they all have one of the following basic shapes:

The precise shape and construction of footballs is typically specified as part of the rules and regulations.

The oldest football still in existence, which is thought to have been made circa 1550, was discovered in the roof of Stirling Castle, Scotland, in 1981. The ball is made of leather (possibly from a deer) and a pig's bladder. It has a diameter of between 14–16 cm (5.5–6.3 in), weighs 125 g (4.4 oz) and is currently on display at the Smith Art Gallery and Museum in Stirling.

In Canada and the United States, the term football usually refers to a ball made of cow hide leather, which is required in professional and collegiate football. Footballs used in recreation, and in organised youth leagues, may be made of rubber or plastic materials (the high school football rulebooks still allow the inexpensive all-rubber footballs, though they are less common than leather). Since 1941, Wilson has been the exclusive supplier of leather for National Football League footballs. The arrangement was established by Arnold Horween, who had played and coached in the NFL. Horween Leather Company also supplies leather to Spalding, supplier of balls to the Arena Football League.

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