Contemporary codes of football can be traced back to the codification of these games at English public schools during the nineteenth century. The expanse of the British Empire allowed these rules of football to spread to areas of British influence outside of the directly controlled Empire. By the end of the nineteenth 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. In 1888, The Football League was founded in England, becoming the first of many professional football competitions. During the twentieth century, several of the various kinds of football grew to become some of the most popular team sports in the world.
^Bailey, Steven. Living Sports History: Football at Winchester, Eton and Harrow. The Sports Historian. 1995, 15 (1): 34–53. doi:10.1080/17460269508551675.
^Perkin, Harold. Teaching the nations how to play: sport and society in the British empire and commonwealth. The International Journal of the History of Sport. 1989, 6 (2): 145–155. doi:10.1080/09523368908713685.
^The first game of American football is widely cited as a game played on November 6, 1869, between two college teams, Rutgers and Princeton. But the game was played under rules based on the association football rules of the time. During the latter half of the 1870s, colleges playing association football switched to the Rugby code.
^In 1845, the first rules of rugby were written by Rugby School pupils. But various rules of rugby had existed until the foundation of the 橄欖球聯合會 in 1871.