Association football is one of a family of football codes that emerged from various ball games played worldwide since antiquity. Within the English-speaking world, the sport is now usually called "football" in Great Britain and most of Ulster in the north of Ireland, whereas people usually call it "soccer" in regions and countries where other codes of football are prevalent, such as Australia,[8] Canada, South Africa, most of Ireland (excluding Ulster),[9] and the United States. A notable exception is New Zealand, where in the first two decades of the 21st century, under the influence of international television, "football" has been gaining prevalence, despite the dominance of other codes of football, namely rugby union and rugby league.[10]

The term soccer comes from Oxford "-er" slang, which was prevalent at the University of Oxford in England from about 1875, and is thought to have been borrowed from the slang of Rugby School. Initially spelt assoccer (a shortening of "association"), it was later reduced to the modern spelling.[11][12] This form of slang also gave rise to rugger for rugby football, fiver and tenner for five pound and ten pound notes, and the now-archaic footer that was also a name for association football.[13] The word soccer arrived at its current form in 1895 and was first recorded in 1889 in the earlier form of socca.