Football is a family of team sports that involve, to varying degrees, kicking a ball to score a goal. Unqualified, the word football normally means the form of football that is the most popular where the word is used. Sports commonly called football include association football (known as soccer in Australia, Canada, South Africa, the United States, and sometimes in Ireland and New Zealand); Australian rules football; Gaelic football; gridiron football (specifically American football, Arena football, or Canadian football); International rules football; rugby league football; and rugby union football.[1] These various forms of football share, to varying degrees, common origins and are known as "football codes".
There are a number of references to traditional, ancient, or prehistoric ball games played in many different parts of the world.[2][3][4] Contemporary codes of football can be traced back to the codification of these games at English public schools during the 19th century, itself an outgrowth of medieval football.[5][6] The expansion and cultural power of the British Empire allowed these rules of football to spread to areas of British influence outside the directly controlled Empire.[7] By the end of the 19th century, distinct regional codes were already developing: Gaelic football, for example, deliberately incorporated the rules of local traditional football games in order to maintain their heritage.[8] In 1888, the Football League was founded in England, becoming the first of many professional football associations. During the 20th century, several of the various kinds of football grew to become some of the most popular team sports in the world.[9]
The various codes of football share certain common elements and can be grouped into two main classes of football: carrying codes like American football, Canadian football, Australian football, rugby union and rugby league, where the ball is moved about the field while being held in the hands or thrown, and kicking codes such as association football and Gaelic football, where the ball is moved primarily with the feet, and where handling is strictly limited.[10]
In all codes, common skills include passing, tackling, evasion of tackles, catching and kicking.[10] In most codes, there are rules restricting the movement of players offside, and players scoring a goal must put the ball either under or over a crossbar between the goalposts.
There are conflicting explanations of the origin of the word "football". It is widely assumed that the word "football" (or the phrase "foot ball") refers to the action of the foot kicking a ball.[12] There is an alternative explanation, which is that football originally referred to a variety of games in medieval Europe that were played on foot.[13] There is no conclusive evidence for either explanation.
The Chinese competitive game cuju (蹴鞠) resembles modern association football.[14] It existed during the Han dynasty and possibly the Qin dynasty, in the second and third centuries BC, attested by descriptions in a military manual.[15][16] The Japanese version of cuju is kemari (蹴鞠), and was developed during the Asuka period.[17] This is known to have been played within the Japanese imperial court in Kyoto from about 600 AD. In kemari, several people stand in a circle and kick a ball to each other, trying not to let the ball drop to the ground (much like keepie uppie).