A ball sport played by two (singles) or four players (doubles squash) in a four-walled court with a small, hollow rubber ball. The players must alternate in striking the ball with their racquet and hit the ball onto the playable surfaces of the four walls of the court.
The players spin a racket to decide who serves first. This player starts the first rally by electing to serve from either the left or right service box. For a legal serve, one of the server's feet must be in the service box, not touching any part of the service box lines, as the player strikes the ball.
After being struck by the racket, the ball must strike the front wall above the service line and below the out-line and land in the opposite back quarter court. The receiving player can choose to volley a serve after it has hit the front wall. If the server wins the point, the two players switch sides for the following point.
After the serve, the players take turns hitting the ball against the front wall, above the tin and below the out- line. The ball may strike the side or back walls at any time, as long as it hits below the out-line. It must not hit the floor after hitting the racket and before hitting the front wall. A ball landing on either the out-line or the line along the top of the tin is considered to be out. After the ball hits the front wall, it is allowed to bounce once on the floor (and any number of times against the side or back walls) before a player must return it. Players may move anywhere around the court but accidental or deliberate obstruction of the other player's movements is forbidden and could result in a let or a stroke. Players typically return to the center of the court after making a shot.
Squash can be played with different scoring systems and players in amateur matches can arbitrarily set a point total to determine a winner. Currently, most games are played according to the point-a-rally system (PARS) to 11 points although many players continue to play by English or Hand-In-Hand-Out (HiHo) scoring to 9 whereby only the server may win a point. Players often experience PARS and Hi-Ho as vastly different games requiring different tactics and player attributes. In addition to English or Hand-In-Hand-Out and PARS, there is American scoring by which games are played to 15 instead of 11 as in PARS.
The squash court is a playing surface surrounded by four walls. The court surface contains a front line separating the front and back of the court and a half court line, separating the left and the right-hand sides of the back portion of the court, creating three 'boxes': the front half, the back left quarter and the back right quarter. Both the back two boxes contain smaller service boxes. The floor-markings on a squash court are only relevant during serves.
There are four walls to a squash court. The front wall, on which three parallel lines are marked, has the largest playing surface, whilst the back wall, which typically contains the entrance to the court, has the smallest. The out-line runs along the top of the front wall, descending along the side walls to the back wall. There are no other markings on the side or back walls. Shots struck above or touching the out-line, on any wall, are out. The bottom line of the front wall marks the top of the 'tin', a half meter-high metal area which if struck means that the ball is out. In this way the tin can be seen as analogous to the net in other racket sports such as tennis. The middle line of the front wall is the service line and is only relevant during serves.