Squash is 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 game was formerly called squash rackets, a reference to the "squashable" soft ball used in the game (compared with the harder ball used in its sister game rackets).
The rackets have changed in a similar way to those used in tennis. Squash rackets used to be made out of laminated timber. In the 1980s, construction shifted to lighter materials (such as aluminium and graphite) with small additions of components like Kevlar, boron and titanium. Natural "gut" strings were also replaced with synthetic strings.