Football refers to a number of sports that involve, to varying degrees, kicking a ball with the foot to score a goal. The most popular of these sports worldwide is association football, more commonly known as just "football" or "soccer". Unqualified, the word football applies to whichever form of football is the most popular in the regional context in which the word appears, including association football, as well as American football, Australian rules football, Canadian football,Gaelic football, rugby league, rugby union and other related games. These variations of football are known as football codes.
American football evolved from early forms of rugby, particularly rugby union, and association football (soccer). The first game was played on November 6, 1869 under a set of rules resembling those of rugby and soccer. A set of rule changes instituted from 1880 onward by Walter Camp established the snap, eleven-player teams and downs. Later rule changes legalized the forward pass, created the neutral zone and specified the width of the football.