Racquetball is a racquet sport played with a hollow rubber ball in an indoor or outdoor court. Joseph Sobek is credited with inventing the modern sport of racquetball in 1950, 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.