Here you can read all you need to know about Rugby Union. The positions, scrum, lineout, and the point system.
You play rugby with 15 players. There are two kinds of players. The Forwards are usually heavy and not very fast the numbers of the Forwards are numbers 1 to 8. The backs numbers 9 to 15 are usually more lightly built and faster.
A scrum is a way of restarting the game safely and fairly after a minor infringement. It is awarded when the ball has been knocked or passed forward if a player takes the ball over his own try line and puts the ball down, when a player is accidentally offside or when the ball is trapped in a ruck or maul with no realistic chance of being retrieved. A team may also opt for a scrum if awarded a penalty. A scrum is formed by the eight forwards from each team binding together in three rows. The front row consists of the two props (loosehead and tighthead) either side of the hooker. The second row consists of two locks and the two flankers. Behind the second row is the number 8. This formation is known as the 3–4–1 formation. Once a scrum has formed the scrum-half from the team awarded the feed rolls the ball into the gap between the two front-rows known as the tunnel. The two hookers then compete for possession by hooking the ball backward's with their feet, while each pack tries to push the opposing pack backward's to help gain possession. The side that wins possession transfers the ball to the back of the scrum, where it is picked up either by the number 8 or by the scrum-half.
When the ball leaves the side of the field, a lineout is awarded against the team which last touched the ball. Forward players from each team line up a meter apart, perpendicular to the touchline and between 5 m and 15 m from the touchline. The ball is thrown from the touchline down the center of the lines of forwards by a player (usually the hooker). The exception to this is when the ball went out from a penalty, in which case the side who gained the penalty throws the ball in. Both sides compete for the ball and players may lift their teammates. A jumping player cannot be tackled until they stand and only shoulder-to-shoulder contact is allowed; deliberate infringement of this law is dangerous play and results in a penalty kick.
Rugby union is played with two teams of 15 players. The team that has the most points wins the match. Points can be scored in several ways: a try, scored by grounding the ball in the in-goal area (between the goal line and the dead-ball line), is worth 5 points and a subsequent conversion kick scores 2 points; a successful penalty kick or a drop goal each score 3 points. The values of each of these scoring methods have been changed over the years.