Football (ball)

Football (ball)

A football is an inflated ball used to play one of the various sports known as football. The first balls were made of natural materials, such as an inflated pig bladder, sometimes inside a leather cover, which has given rise to the United States 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:

1. a sphere: used in soccer (commonly called football in large parts of the world) and Gaelic football
2. a prolate spheroid ('egg-shaped')
   • either with rounded ends: used in the rugby codes and Australian football
   • or with more pointed ends: used in American football and Canadian football

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 1540, 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.