Soccer (Association football) is a ball game played by two teams, each of 11 players. The object of the game is to put the ball into the opponents’ goal, and the winning team is the one that scores the greater number of goals.

The field is rectangular and must be 50-100yd wide and 100-130yd long.
At either end there is a goal and a goal area enclosed in the larger penalty area. The posts and crossbar of the goals must be of equal width and of the same width as the goal line.
The touchlines and the goal lines are part of the playing area.
At each corner of the field is a flag on a post that is at least 5ft high and must not have a pointed top. Flags on either side of the centre line are optional, but must be set back at least 1yd from the touchline.

A referee controls the game and is assisted by two linesmen The referee: acts as timekeeper and keeps a record of the game; enforces the laws; stops the game at injuries, infringements, etc, and restarts it appropriately; cautions or sends off offenders; may end the game because of bad weather, interference by spectators, etc.
The linesmen, one on each touchline, indicate when the ball is out of play, and which side has the right to put the ball into play again with a throw in, corner kick, or goal kick. They raise their flags to indicate any infringement, and the referee may choose whether or not to act on this signal.

Each team has 11 players, one of whom is the goalkeeper.

A maximum of two substitutes is permitted, depending upon the competition and for any reason. They may have to be named before the game. Once substituted, a player may not return to the game. The referee must be informed of any substitution.
A player, who has been ordered off after play has started, may not be replaced.
In the event of an injury an outfield player may become the goalkeeper, provided he obtains the referee’s permission and wears a distinctive jersey.

The game is played in two halves of 45 minutes each; the teams change ends at halftime. The half time interval may not exceed five minutes, except by consent of the referee.
The referee adds on time for moments lost through injuries, time wasting, etc. Time is also extended to allow a penalty kick to be taken at the end of either period.

The ball is made of leather or other approved material. At the start of a game, it must weigh 14-16oz and should be inflated to a pressure of 0.6-1.1 atmosphere (=600-1100gr/cm2) at sea level.
Its circumference should be 27-28ins.
The ball may not be changed during the game without the referee’s permission.

Except at throw ins, the goalkeeper is the only player allowed to play the ball with his hands or arms, and he may only do so within his own penalty area.
A player may, however, use any other part of the body in order to stop, control, or pass the ball, move with it, or score. He may use his:
1 feet
2 head
3 thigh
4 chest

http://www.nzsoccer.com