Australian rules football is a football variant played between two teams of 18 players plus 4 interchange players outdoors on large oval-shaped grass fields, with a ball in the shape of a prolate spheroid. The primary aim of the game is to score goals by kicking the ball between the middle two posts of the opposing goal.
Players may use any part of their body to advance the ball. The primary methods are kicking, handballing and running with the ball. There are restrictions on how the ball can be handled, for example players running with the ball must intermittently bounce or touch it on the ground, throwing the ball is not allowed and players must not get caught holding the ball. Unlike most similar sports, there is no offside rule and players can roam the field freely. Possession of the ball is in dispute at all times except when a free kick is paid.
A distinctive feature of the game is the mark, where players anywhere on the field who catch a ball from a kick (with specific conditions), are awarded a free kick. Australian rules is a contact sport in which players can tackle using their hands or use their whole body to obstruct opponents. Dangerous physical contact (such as a pushing an opponent in the back), interference when marking and deliberately slowing the play are discouraged with free kicks, distance penalties or suspension. Frequent physical contests, aerial marking or “speckies”, fast movement of both players and the ball and high scoring are the game’s main attributes as a spectator sport.
[from Wikipedia entry]