Rugby is played between two teams; each team starts the match with 15 players on the field and may make replacements (for injury) or substitutions (tactical changes). In international matches, up to seven replacements/substitutes are allowed; in domestic or cross-border tournaments, at the discretion of the responsible national union(s), the number may be increased to eight, of whom three must be sufficiently trained and experienced to provide cover for the three front row positions. Players in a team are divided into eight forwards (two more than in rugby league) and seven backs. Forwards are generally bigger and stronger, and take part in the scrum and lineout, while backs are generally smaller but faster, more agile and often the main points scorers for the team.
Points can be scored in several ways: a try, scored by grounding the ball in the in-goal area, 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. The team which scores more points wins the game. At the beginning of the game, the captains and the referee toss a coin to decide which team will kick off first. 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 back. If the player with the ball is tackled, frequently a ruck will result.
Forward passing (throwing the ball ahead to another player) is not allowed. The ball tends to be moved forward in three ways – by kicking, by a player running with it, or within a scrum or a ruck (formerly also a maul). Unlike in American football, “blocking” is not allowed, so 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. When the ball leaves the side of the field, a lineout is awarded against the team which last touched the ball. A number of players from both teams line up, at least 5m from the sideline, and the ball is thrown in by the hooker. Lineouts are one of the chief differences between the two rugby codes, as they do not occur in rugby league.
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. Stoppages for injury or to allow the referee to take disciplinary action, do not count as part of the playing time, so that the elapsed time is usually longer than 80 minutes. Unlike in many other sports, there are no “time outs”. The referee is responsible for keeping time, even when—as in many professional tournaments—he is assisted by an official time-keeper; when time has expired, whether at the end of the first half, or at the end of the game, the referee will wait until the ball is ‘dead’ before blowing for half-time or full-time.
The field of play on a rugby pitch is as near as possible to a maximum of 100m long, and 70m wide. There are several lines crossing it, notably the half way line, the goal line/try line (on which the goal posts are located), the “twenty two”, which is 22m from the goal, and the dead ball line, which is 10m behind the goal line. Tries are scored between the goal line, and the dead ball line. A ball over the dead ball line is out of play. Rugby goalposts are H-shaped, and consist of two poles, 5.6m apart, connected by a horizontal crossbar 3m above the ground. Unlike some other sports there are no goalkeepers, and the section underneath the crossbar has no special meaning, although a try scored between or close to the posts makes for an easier conversion. The original pitch dimensions were in imperial units, but have since been converted to the metric system.
There are generally three match officials: a referee, and two touch judges, who indicate that the ball is “in touch” and other decisions with their flags. In addition, for matches in high level competitions, there is often a television match offical (TMO; popularly called the “video referee”), to assist with certain decisions, linked up to the referee by radio. The referees have a system of hand signals to indicate their decisions.
Common offences include high tackles, collapsing the scrum, not releasing the ball when on the ground or being off-side. Penalties can be taken by the non-offending team in various ways: taking a short, tap kick then running with the ball, kicking the ball from hand (punting) for field position, place kicking (for goal) or choosing a scrum. Players may be sent off (signalled by a red card) or temporarily “sin-binned” for ten minutes (yellow card) for foul play, and may not be replaced.