There are plenty of laws every player - from Sunday league right up to international level - must follow; some simple, others complicated. The interpretation of these is at the discretion of the referee, supported by additional judges, two on each touchline.

A match lasts 80 minutes. Any stoppages for injuries result in the equivalent amount of time being added on to the end of that particular 40-minute half. Substitutions are only permitted if a player is forced to retire hurt.

Rugby Union

A rugby union match comprise two sides of 15 players each trying to score as many points as possible by carrying, passing, kicking and grounding the ball in opposing team's goal-line at the end of the pitch. A team can score points in the following manners: a try, worth five points, occurs when a player grounds the ball in the goal area of the opposing team; a penalty try, also worth five points, is given when an opponent commits foul play when they were on course to score a try; a conversion goal, worth two points, is kicked through the upper sector of the H-shaped goal from a mark in a direct line from where it was touched down for a try; a penalty, worth three points, is scored when a player kicks a goal from a penalty kick and an opponent commits a foul; and lastly, a dropped goal, also worth three points, can be scored when a player kicks a goal from a drop kick in regular play.

There are off and onside rules in rugby. Offside play basically means that a player is in front of a teammate running with the ball, or in front of a teammate who last used the ball. Players get disciplined for breaking both during the course of play. For example, in general play, offsides means a player is temporarily out of the game and will be penalized if he takes part in the action. The player must either be put onside by a teammate or opposition, or move away from the ball.

At the time of a kick, if a player is in front of a teammate who kicked the ball ahead, he has to retire until the player or an onside teammate puts him onside. Then, if a player knocks-on and an offside teammate plays the ball, the offside player may be penalized if his playing the ball stopped the opposition from gaining advantage. During a scrum, ruck, maul or line-out, if a player is offside in the pertinent passages of play and crosses the imaginary offside line - which is behind his teammate's feet in a scrum - he can be penalized.

During open play, the ball must be either kicked or carried forward. If it is passed to another player, it has to be passed backwards, so all supporting players tend to be behind the ball when a team-mate is running with it. If a ball goes into touch, you have a lineout, in which the forwards from either side form two parallel lines at the point where the ball went out of play. The ball is then thrown down those two lines, the players jump to retrieve it, and play continues.

Rugby League

This too is an 80-minute game but with 13 players. Tries are scored in the same manners as in rugby union, but are worth four points. The following conversion receives two points. Penalty kicks are awarded two points, while drop-goals receive one.

Sides are allowed six tackles in their move towards the opposing goal-line, and after each, the player in possession has to roll the ball backwards under his foot to the next receiving players. Unlike in rugby union, the player who has been tackled doesn't have to release the ball.

If a team fails to score after six tackles, the ball is forfeited back to the other side. The final kick can be a touch-kick, but the ball must bounce inside the touchline before going out of play. There are touchlines either side of the pitch, as well as at either ends, which are known as "touch-in-goal".

If a defending opponent carries the ball back over his own try-line, makes a touch-kick that doesn't bounce inside the line, is tackled in his own goal area or is the last man to touch the ball before it goes out of play, the attacking team can force the defending team to drop out of their own goal area. The defending team then has to kick the ball out from the middles of its own goal-line at least ten meters.

As for the offside penalties, if a player is standing in a forward position from a team-mate with the ball, but attempting to take part in the play, he is offside. If he isn't playing for the ball, he must drop back into position quickly to avoid a penalty being given. There are no line-outs in rugby league.