Football is the word given to a number of similar team sports, all of which involve (to varying degrees) kicking a ball with the foot in an attempt to score a goal. The most popular of these sports worldwide is association football, more commonly known as just "football" or "soccer". The English language word "football" is also applied to "gridiron football" (a name associated with the North American sports, especially American football and Canadian football), Australian football, Gaelic football, rugby football (rugby league and rugby union), and related games. Each of these codes (specific sets of rules, or the games defined by them) is referred to as "football".