The offside rule in rugby is similar to that in soccer, and it can be a bit confusing to understand, especially for those new to the game.
Basically, the offside line moves continuously up and down the pitch as the ball moves. The ball creates the offside line, and players are not allowed to participate in the play if they are on their opponent's side of the ball. A player is offside if he is in front of the ball when a teammate is playing it.
Just being offside is not a penalty, but attempting to play the ball while being offside is what triggers a penalty to be called.
Players who have the ball can be stopped by being tackled and brought to the ground. The tackled player has to release the ball and roll away from it to allow other players who are on their feet to play the ball.
When a player is tackled and the ball released, players from each team converge over the ball and bind together like on a scrum, attempting to push the opposing players backwards.
This action is known as a ruck.
The ball can't be picked up by any player until it emerges out of the ruck. When this happens, the ruck ends and play continues.
A maul is similar to a ruck except that the group of players surrounds a ball carrier who is still standing. The maul ends when the ball emerges or the player with the ball is able to run out of the middle.
Players may not:
Penalties are common in rugby, and they usually result in the non-offending team getting the chance to kick the ball to gain field advantage. Here are some of the more common penalties you'll see in the basic rugby rules:
A penalty kick is awarded after a serious rule violation. The offending team has to back away 10 yards while their opponent gets a free kick.
If they're close enough, they can attempt to score by kicking the ball through the goalposts.
Otherwise, they may try to kick the ball down field to gain better field position.
They also have the option of tapping the ball with their foot and picking it up to run with it.
A free kick is awarded for a less serious rule infraction. It's similar to a penalty kick, but the kicking team may not try to kick a goal.
If a player commits a serious violation, the referee may send him to a location behind the goal area where he will sit out of the game for a certain period of time. Play continues with his team playing short-handed until he is allowed to re-enter the game.
In extreme cases of dangerous or reckless play, a player may be ejected from the game and not allowed to return or be replaced by a substitute.