In sport, a cap is a player's appearance in a game at international level. The term dates from the practice in the United Kingdom of awarding a cap to every player in an international match of rugby football and association football. In the early days of football, the concept of each team wearing a set of matching shirts had not been universally adopted, so each side would distinguish itself from the other by wearing a specific sort of cap.
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An early illustration of the first international football match between Scotland and England in 1872 shows the Scottish players wearing cowls, and the English wearing a variety of school caps. The practice was first approved on 10 May 1886 for association football after a proposal made by N. Lane Jackson, founder of the Corinthians:
The act of awarding a cap is now international and is applied to other sports. Although in some sports physical caps may not now always be given (whether at all or for each appearance) the term "cap" for an international or other appearance has been retained as an indicator of the number of occasions on which a sportsperson has represented a team in a particular sport. Thus, a "cap" is awarded for each game played and so a player who has played x games, for the team, is said to have been capped x times or have won x caps.
The practice of awarding a physical cap varies from sport to sport. It may be awarded before a player's debut or, particularly for national teams, a commemorative cap may be awarded after a player reaches the 100th cap.