Indoor game played on an enclosed court. It is regarded as the forerunner of many racket and ball games. Although first played in the Middle Ages, rackets developed in the 18th century and was played against the walls of London buildings. See squash. The Fleet Prison was a popular venue. It is played on a court usually 18.3 m/60 ft long by 9.1 m/30 ft wide, by two or four persons each with a racket about 75 cm/2.5 ft long, weighing 255 g/9 oz. The ball is 25 mm/1 in in diameter and weighs 28 g/1 oz. Play begins from a service box -- one is marked at each side of mid-court -- and the ball must hit above a 2.75 m/9 ft line on the end wall. After service it may be played anywhere above a line 68.5 cm/27 in high on the end wall, the general rules of tennis applying thereafter.