The lineout is a common way of restarting the game after the ball goes out of bounds, or into touch, which is the area outside of the touch lines. There are many aspects to this manoeuvre — the following is a brief description of what it is.
A lineout happens when the ball goes into touch. This can be either accidental, such as when a player fails to catch a pass and the ball goes over the sideline, or it can be tactical, such as tackling the opposing ball carrier over the touch line, or kicking the ball into touch. By putting the ball in to touch intentionally, a line out can be used as an opportunity to win possession of the ball as well as gain further territory.
At the start of a lineout, the forwards position themselves by the touch line where the ball went out of bounds. There, the opposing forwards form two lines that are one meter apart and perpendicular to the touch line.
The hooker (from the team that didn’t knock the ball out of bounds) throws the ball from the touch line straight down the middle of the two opposing lines of forwards. This is called a throw–in. The throw–in is usually awarded to the side that doesn’t knock the ball into touch. However, if the ball is kicked into touch by the team that is awarded a penalty, then that team will get the throw–in.
Once the ball is thrown in, both teams attempt to gain possession of it. Any player in the line out may try to catch the ball. Players are usually lifted up by their teammates in order to catch the ball. The team throwing in the ball usually has an advantage because they shout out codes, so they know exactly who in the lineout the ball will be thrown to. While it may be easier for the side that has the throw–in to gain possession, quick thinking and skillful tactics can enable either side to win the ball.
When the ball is caught, it can either be held onto to form a maul, or be passed back to the receiver, usually the halfback, to resume an attacking advantage.