From Encyc

Football is a term used to describe a wide variety of sports that use a foot and a ball, including but not limited to soccer, Gaelic football, American football, Australian Rules football, Rugby including both Rugby League and Rugby Union. In Australia, a total of 4 separate sports that are popular are referred to as football - Australian Rules, Rugby League, Rugby Union and Soccer - depending on where you live.

Internationally, outside of Ireland, Australia, United States, New Zealand and countries in which other brands of football is popular, soccer is typically referred to simply as football.

Technically speaking, Football is not a sport but a range of sports that involve you kicking a ball with your foot, and could be correctly described as the sport you are playing if you kick a ball with your foot, regardless of the sport's official name. The sports which, in various countries, refer to themselves as football are using colloquial versions of it.

Ireland is the only country that does not refer to any individual sport typically as football, due to the equal popularity of soccer and Gaelic football.