what is the point of a scrum in rugby

In rugby, a scrum is a way of restarting play after a minor infringement of the Laws or when the ball becomes unplayable in a ruck or maul. The scrum serves to concentrate all the forwards and the scrum-halves in one place on the field, providing the opportunity for the backs to mount an attack using the space created elsewhere. The point of a scrum is to gain possession of the ball. The team who throws the ball into the scrum usually retains possession, because the hooker and scrum-half can synchronise their actions. Once possession has been secured, a team can keep the ball on the ground and in the scrum and attempt to drive the opposition. The scrum involves the designated forwards of both teams, which in 15-a-side rugby there are eight players in the scrum on each team and in rugby sevens each side has three.