Scrums are often used to restart play throughout the game. This could be for a number of reasons, such as: due to there being a ‘knock on’, or a forward pass or because a team member is accidentally offside.
If these happen and there is no advantage for the opposing team, play is stopped and a scrum is formed.
A scrum is formed by the 8 forward team members on both teams and you have 2 props, 1 either side of the hooker. These players hook onto the other team at the front of the formation.
Scrumhalf (player 9) places the ball into the scrum, this is the team that has the advantage because the opposing team made a mistake. The players in the scrum have to then feed the ball backwards so that it comes out of the scrum behind them and play can continue. Which usually advantages the team that didn’t make the mistake.
The ball has to exit the rear of the scrum smoothly, the opposing team can try and stop this so that they can win possession by pushing against the team and even turning it sideways so that they can obstruct clean release of the ball. As well as this, it means that the team winning the ball are not heading in the right direction and therefore not covering distance on the pitch.