The scrum is a means of restarting play after a stoppage which has been caused by a minor infringement of the Laws (for example, a forward pass or knock-on) or the ball becoming unplayable in a ruck or maul.
The lineout is a means of restarting the game after the ball, or a player carrying the ball, crosses the touchline. The opponents of the team who last held or touched the ball, prior to it going out of play, throw the ball into the lineout.
Starting and restarting: You start each half of the game with a drop kick. You also restart in the same manner after each score.