Racquetball is a racquet sport played with a hollow rubber ball in an indoor or outdoor court. Joe Sobek is credited with inventing the modern sport of racquetball in 1950 (the outdoor, one-wall game goes back to at least 1910 in N.Y.C.), adding a stringed racquet to paddleball in order to increase velocity and control. Unlike most racquet sports, such as tennis and badminton, there is no net to hit the ball over, and unlike squash no tin (out of bounds area at the bottom of front wall) to hit the ball above. Also, the court’s walls, floor, and ceiling are legal playing surfaces, with the exception of court-specific designated hinders being out-of-bounds.
Play begins with the serve. The serving player must bounce the ball on the floor once and hit it directly to the front wall, making the ball hit the floor beyond the short line; otherwise the serve counts as a fault.The ball may touch one side wall, but not two, prior to hitting the floor; hitting both side walls after the front wall (but before the floor) is a “three wall serve,” and a fault. Also, serving the ball into the front wall so that it rebounds to the back wall without hitting the floor first is a long serve, and a fault.
Other fault serves include a ceiling serve in which the ball touches the ceiling after the front wall and serving before the receiving player is ready. Also, the server must wait until the ball passes the short line before stepping out of the service box, otherwise it is a fault serve.
If the server hits the ball directly to any surface other than the front wall the server immediately loses serve regardless of whether it was first or second serve.
After the ball bounces behind the short line, or passes the receiving line, the ball is in play and the opposing player(s) may play it.
Usually, the server is allowed two opportunities (called first serve and second serve) to put the ball into play (two serve rule), although elite level competitions often allow the server only one opportunity (one serve rule).
After a successful serve, players alternate hitting the ball against the front wall. The player returning the hit may allow the ball to bounce once on the floor or hit the ball on the fly. However, once the player returning the shot has hit the ball, either before bouncing on the floor or after one bounce, it must strike the front wall before it hits the floor. Unlike during the serve, a ball in play may touch as many walls, including the ceiling, as necessary so long as it reaches the front wall without striking the floor.
Reference: Wikipedia Racquetball