Scrum, which is short for scrummage, is a term used to refer to a specific play used in rugby football. The word was created as a modification of the word scrimmage, which is still used in Canadian and American football to refer to a similar type of play.
When used in rugby league football, the term scrum refers to a play in which the game is restarted because the ball has gone into touch or there has been an accidental infringement. In union rugby, however, the term is only used when a game is restarted from an accidental infringement. In union rugby, a scrum is a very important play and happens quite frequently.
In union rugby, each team places eight forwards in a three-two-three formation before the scrum is formed. The front row includes two prop forwards and the hooker. The two players in the second row are called locks, while the back row consists of the number eight with a flanker on either side.
When play begins on a scrum, both teams move forward and crouch down. After the referee gives the proper signal, the players in the front rows interlock their hands. The ball is then returned to play by being thrown into the tunnel created by the interlocked heads. The hookers on each team compete for possession of the ball by using only their feet. The hooker that gains possession typically kicks the ball to the back of the scrum so the number eight can take possession of the ball.
The team with the most powerful scrum will be able to gain possession of the ball. The scrum is also a dangerous play, as the players in the front row can easily break their necks if the play is improperly executed. In fact, the play is considered so dangerous that a scrum may be uncontested if either team does not have the properly trained athletes to play in the front row.
In rugby league, a scrum is played in much the same way. The formation, however, is a bit different. To start the scrum, six players make the forward pack. It consists of a tight-head prop and a loose head prop in the front row, a hooker and two forwards in the second row, and a loose forward in the third row.