Field & Equipment
Of course, it's called a pitch, not a field. The Australian football pitch is an oval, 135-185 meters (442-606 feet) long and 110-155 meters (360-508 feet) wide. The recommended size is 165 by 135 meters.
The center circle is 3 meters in diameter and is enclosed by the center square, which is 45 meters on each side. The mid-line divides the circle laterally and extends no more than two meters beyond the circle on each side.
At each end of the pitch are a pair of goal posts, 6.4 meters (21 feet, 10 inches) apart and 6 meters high. There are also two behind posts, each 6.4 meters outside a goal post and at least 3 meters high. A straight line is drawn between the behind posts. The portion of the line between the goal posts is the goal line. A portion of the line between a goal post and a behind post is a behind line.
The goal square, despite its name, is a rectangle that extends 9 meters into the pitch from the goal posts. The lines enclosing the goal square are called the kickoff lines.
The 50-meter line is an arc drawn on the ground from sideline to sideline, with its apex 50 meters from a point midway between the goal posts.
The ball is a leather-covered spheroid with a long circumference of 725mm (about 29 inches) and a short circumference of 550mm (about 22 inches). It weighs 454-482 grams (17 ounces) and is inflated to about 10 pounds per square inch.
Players wear no protective equipment, only sleeveless shirts, shorts, socks, and studded boats.
Teams & Officials
A team is usually made up of 20 to 22 players, but only 18 at a time are on the field. At any time, a substitute may be interchanged with one of the other participating players. The player he's replacing must leave the field before the interchange player goes on. Both players must pass through the interchange area, which is marked by two lines, each 7.5 meters from the middle of the pitch. There's one exception to this rule: If a player is seriously injured, his replacement may enter the game while the injured player is still on the field.
There are five officials. The field umpire, is in overall control of the game, moves around the pitch with the ball, following the action. The two boundary umpires, on opposite sides of the pitch, are primarily responsible for determining when the ball has gone out of bounds. The two goal umpires, stationed at opposite ends of the field behind the goal posts, are primarily responsible for determining whether a goal or behind has been scored.
Duration
A game is made up of four quarters of 25 minutes each, with breaks of 3 minutes between the first and second quarters, 15 minutes at halftime, and 5 minutes between the third and fourth quarters.
The timekeepers sound a siren when time has expired in a quarter. However, the period doesn't end until the field umpire blows his whistle. He may allow play to continue for a time if there has been an unusual delay.
A score is allowed after time has run out, if the ball was already moving toward the goal, the player was awarded a free kick, or the player took a mark before the siren sounded.
The team with the most points at the end of the fourth period is the winner. If the scores are even, the match is a draw. There's no provision for overtime.
Scoring
There are two ways to score, a goal (worth 6 points) and a behind (worth 1 point).
It's a goal if a member of the attacking team kicks the ball over the goal line between the goalposts without it touching either the posts or another player.
A behind is scored when the ball goes between the goalposts without qualifying as a goal (e. g., when it touches another player in transit); the ball touches or passes over a goalpost; the ball passes over a behind line without touching a behind post; or the ball is kicked or carried over the behind line or goal line by a defender.
After a behind has been scored, the defending team has to kick off from within the goal square. No other player is allowed with 5 meters of the kickoff lines until the ball has been kicked. Once the ball has been kicked beyond the kickoff lines, any player, including the kicker, may gain possession.
Bouncing the Ball
The team that wins the pre-game coin toss chooses which goal it will defend. Teams change ends after each quarter.
The field umpire begins a quarter by bouncing the ball in the center circle. Until the ball touches the ground, only four players per team are allowed inside the center square, and none of them is allowed inside the circle.
If the ball can't be bounced effectively because the ground is wet or muddy, the judge can elect to toss it into the air, after informing both teams.
Bouncing the ball is also used to restart play after a goal; if the ball leaves the field of play after a bounce, without having been touched by a player; when a player kicking off from behind kicks from beyond the kickoff lines; when there's doubt as to which player has called mark; or when the goal umpire cannot see whether the ball has crossed the goal line.
Only one player from each team can contest for the ball unless the umpire decides that the ball took a bad bounce, in which he calls "Play on" and any player may go after it.
Advancing the Ball
A player in possession of the ball can run with it or kick it, but may not throw it. The only legal way to pass the ball is to "handball" it by holding it one hand and hitting with the fist of the other hand. If the player runs with the ball, he must bounce it or touch it to the ground once every 10 meters (about 33 feet).
A defender may tackle the player with the ball by using his hip, chest, shoulder, arms, or open hands, but a tackle below the waist or above the shoulders isn't allowed. The player with the ball is allowed to use an open hand to fend off a prospective tackler by pushing him in the chest, shoulder, or side.
An attacking player who doesn't have the ball may be pushed in the side or chest with fair and reasonable force if he is within 5 meters (about 17 feet) of the ball.
If the player in possession of the ball is held by a defender firmly enough to stop or greatly reduce his progress, he must get rid of the ball by kicking or handballing it. If he doesn't do this within a reasonable time, the field umpire can award a free kick to the other team.
Marks
If a player catches and holds the ball directly from the kick of a player at least 10 metres (33 feet) away, he is awarded a mark. The ball must not have touched another player, but if it strikes an official and is caught before it touches the ground, the mark is awarded.
After a mark, the player is allowed an unobstructed kick from any point behind the spot where the mark was made. Only one opponent is allowed to stand at the mark; no other player is allowed within an imaginary 10-meter semicircle behind the mark.
If a defender moves into the semicircle before the kick, it is called "crossing the mark." If a goal is scored, it counts. If a goal is not scored, the player who made the mark is allowed another kick.
Free Kicks
A free kick is awarded to the nearest player if an opponent deliberately infringes at the center bounce; interferes with the bouncing of the ball by the field umpire; interferes with the field umpire during the match; interferes with an opponent when the ball is out of play or is more than 5 metres away; holds back or trips a player who has kicked or handballed the ball; trips or kicks an opponent, or attempts to do so; strikes or attempts to strike an opponent; grabs an opponent below the knee or above the neck (including the upper shoulder), charges an opponent; pushes an opponent from behind, except when legitimately trying for a mark; pushes an opponent in the face; pushes an opponent who is in the air; handballs the ball incorrectly; throws or hands the ball to another player; infringes the rules on running with the ball; puts the ball out of bounds without it being touched by another player; kicks the ball out of bounds when kicking off from a behind; kicks the ball out of bounds without it touching the ground; interferes with an opponent while the ball is out of bounds; or infringes the rules on holding the ball.
If the offense was committed against a player after he disposed of the ball by kicking or handballing it, the team may elect to take the kick from where the ball touched the ground, where the ball was caught; where the ball was marked; where the ball went out of play, where the offense occurred.
The player can take the free kick from any point behind where it was awarded. No other player may be within 10 meters, and only one opponent is allowed at that distance.
If a defender deliberately delays a free kick or mark, it may be advanced a maximum of 50 metres (about 164 feet) toward the offending team's goal.
If the offending team commits a second offense before the free kick is taken, the free kick can be taken from the place where the second offense took place, if that's to the benefit of the kicking team. If the defending team commits another offense during a successful free kick at goal, the goal counts. If the kick results in a behind, another kick is awarded.
Out of Bounds
The ball is out of bounds when it is completely outside the boundary line, or when it strikes a behind post after first touching the ground or being touched by a player. If it hits a behind post on the fly and comes back into the field of play, it is still a live ball.
The boundary umpire on the side of the pitch where the ball goes out signals that it is out of bounds by raising an arm. He may also blow his whistle to get the field umpire's attention. With play stopped, the boundary umpire then retrieves the ball and brings it back to the spot where it went out.
If the ball went out of bounds "on the full," meaning that it went out on the fly, directly from a kick, or if a player carried the ball out of bounds, a free kick is awarded to the nearest opponent at the spot. Otherwise, the boundary umpire puts the ball back into play with a throw in from the spot. He throws the ball from over his head toward the center of the field. The throw must be at least 10 meters high and must travel 10 to 15 meters.