Rules:

Rugby union is played between two teams (15 players each) – the one that scores more points wins the game. 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 adrop goal each score 3 points.

Play then starts with a drop kick, with the players chasing the ball into the opposition's territory, and the other side trying to retrieve the ball and advance it. If the ball does not reach the opponent’s 10-metre line the opposing team has two choices: • To have the ball kicked off again, or • To have a scrum at the centre of the half-way line and they throw in the ball. If the player with the ball is tackled, frequently a ruck will result.

Games are divided into 40-minute halves, with a break in the middle. The sides exchange ends of the field after the half-time break.

Positions:

Forwards:

The main responsibilities of the forward players are to gain and retain possession of the ball. Players in these positions are generally bigger and stronger and take part in the scrum and line-out. The forwards are often collectively referred to as the 'pack', especially when in the scrum formation.

Front row: [1,2,3]
The front row consists of three players: two props (the loosehead prop and the tighthead prop) and the hooker. The role of the two props is to support the hooker during scrums, to provide support for the jumpers during line-outs and to provide strength and power in rucks and mauls. The third position in the front row is the hooker. The hooker is a key position in attacking and defensive play and is responsible for winning the ball in the scrum. Hookers normally throw the ball in at line-outs.

Second row: [4,5]
The second row consists of two locks or lock forwards. Locks are usually the tallest players in the team, and specialise as line-out jumpers. The main role of the lock in line-outs is to make a standing jump, often supported by the other forwards, to either collect the thrown ball or ensure the ball comes down on their side. Locks also have an important role in the scrum, binding directly behind the three front row players and providing forward drive.

Back row (Loose Forwards): [6,7,8]
The three positions in the back row are the two flankers and the number 8. The two flanker positions, called the blindside flanker and openside flanker, are the final row in the scrum. They are usually the most mobile forwards in the game. Their main role is to win possession through 'turn overs'. The number 8 packs down between the two locks at the back of the scrum. His role in the scrum is to control the ball after it has been heeled back from the front of the pack and the position provides a link between the forwards and backs during attacking phases.

Backs:

The backs' role is to create and convert point-scoring opportunities. They are generally smaller, faster and more agile than the forwards. Another distinction between the backs and the forwards is that the backs are expected to have superior kicking skills, especially the fly-half and full-back.

Half-backs: [9,10]
The half-backs consist of two positions, the scrum-half and the fly-half. The fly-half is crucial to a team's game plan, orchestrating the teams performance. They are usually the first to receive the ball from the scrum-half following a breakdown, lineout or scrum and need to be decisive with what actions to take and be effective at communicating with the outside backs. Many fly-halfs are also their team's goal kickers. The scrum-half is the link between the forwards and the backs. They receive the ball from the lineout and remove the ball from the back of the scrum, usually passing it to the fly-half. They also feed the scrum and sometimes have to act as a fourth loose forward.

Three quarters: [11,12,13,14]
There are four three quarter positions, the inside centre, outside centre and left and right wings. The centres will attempt to tackle attacking players; whilst in attack they should employ speed and strength to breach opposition defences. The wings are generally positioned on the outside of the backline. Their primary function is to finish off moves and score tries. Wings are usually the fastest players in the team and are elusive runners who use their speed to avoid tackles.

Fullbacks: [15]
The fullback normally positions himself several metres behind the back line. He fields any opposition kicks and is often the last line of defence should an opponent break through the back line. Two of the most important attributes of a good fullback are dependable catching skills and a good kicking game.

Laws:

Passing and kicking:

Forward passing (throwing the ball ahead to another player) is not allowed; the ball can be passed laterally or backwards. The ball tends to be moved forward in three ways — by kicking, by a player running with it or within a scrum or maul. Only the player with the ball may be tackled or rucked. When a ball is knocked forward by a player with his/her arms, a "knock-on" is committed, and play is restarted with a scrum.

Any player may kick the ball forward in an attempt to gain territory. When a player anywhere in the playing area kicks indirectly into touch so that the ball first bounces in the field of play the throw-in is taken where the ball went into touch. If the player kicks directly into touch (i.e. without bouncing in-field first) from within their own 22-metre line the lineout is taken by the opposition where the ball went into touch, but if the ball is kicked into touch directly by a player outside the 22-metre line the lineout is taken level to where the kick was taken.

Breakdowns:

The aim of the defending side is to stop the player with the ball, either by bringing them to ground (a tackle, which is frequently followed by a ruck), or by contesting for possession with the ball-carrier on their feet (a maul). Such a circumstance is called a breakdown and each is governed by a specific law. A player may tackle an opposing player who has the ball by holding them while bringing them to ground. Tacklers cannot tackle above the shoulder (the neck and head are out of bounds), and the tackler has to attempt to wrap their arms around the player being tackled to complete the tackle. It is illegal to push, shoulder-charge, or to trip a player using feet or legs, but hands may be used (this being referred to as a tap-tackle or ankle-tap). Mauls occur after a player with the ball has come into contact with an opponent but the handler remains on his feet; once any combination of at least three players have bound themselves a maul has been set. A ruck is similar to the maul, but in this case the ball has gone to ground with at least three attacking players binding themselves on the ground in an attempt to secure the ball.

Set Pieces:

Lineout:

When the ball leaves the side of the field, a line-out is awarded against the team which last touched the ball. Forward players from each team line up a metre apart, perpendicular to the touchline and between 5 m and 15 m from the touchline.

The ball is thrown from the touchline down the centre of the lines of forwards by a player (usually the hooker) from the team that did not play the ball into touch. 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.

Scrum:

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 is 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 backwards with their feet, while each pack tries to push the opposing pack backwards 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.

Officials and offences:

There are three match officials: a referee, and two assistant referees. The latter, formerly known as touch judges, had the primary function of indicating when the ball had gone "touch"; their role has been expanded and they are now expected to assist the referee in a number of areas, such as watching for foul play and checking off-side lines. The referees have a system of hand signals to indicate their decisions.

Common offences include tackling above the shoulders, collapsing a scrum, ruck or maul, not releasing the ball when on the ground, or being off-side. The non-offending team has a number of options when awarded a penalty: a "tap" kick, when the ball is kicked a very short distance from hand, allowing the kicker to regather the ball and run with it; a punt, when the ball is kicked a long distance from hand, for field position; a place-kick, when the kicker will attempt to score a goal; or a scrum. Players may be sent off (signalled by a red card) or temporarily suspended ("sin-binned") for ten minutes (yellow card) Note: Two yellow cards equals a red card (sending off).

Replacements and substitutions:

During the match, players may be replaced (for injury) or substituted (for tactical reasons). A player who has been replaced may not rejoin play unless he was temporarily replaced to have bleeding controlled; a player who has been substituted may return temporarily, to replace a player who has a blood injury, or permanently, if he is replacing a front-row forward. In international matches, up to seven replacements are allowed.

Bellow is a video guide that explains basic rugby rules. The video is made by England Rugby Union.