Racquetball is a sport played with racquets and a hollow, rubber ball on a special indoor court. Unlike other racquet sports, the walls, floor, and even ceiling of the racquetball court are considered in-bounds. The game is normally played by two players, though there are variations with three or even four (which can get very crowded). Two players games are called singles, three player games are typically called trips or cut-throat, and four player games are called doubles.

A racquetball court is 20 feet wide, 20 feet high, and 40 feet long. The short line of the service box 15 feet from the front wall. The back line of the service box is 20 feet from the front wall.

The player who won the last point is the server. The server stands in the service box and bounces the ball once on the ground, then hits it against the front wall with the racquet. If the ball hits the ceiling, side wall, or floor before hitting the front wall, it is an automatic side out. Bouncing off the front wall, the served ball is required to bounce first somewhere on the floor between the back line of the service box and the back wall. The ball may not hit the ceiling after hitting the front wall after a serve. It can hit one side wall, however. Once it passes the back of the service box, the ball is in play and can be returned.

At this point, players alternate hitting the ball against the front wall. The ball is allowed to bounce on the floor at most one time before being hit against the front wall. After being hit by a player, the ball must not touch the floor at all until hitting the front wall, even if it has not yet bounced. There is no restriction whatsoever on when or how often the ball may hit the side or back walls or the ceiling.

The first player to fail to hit the ball against the front wall before it bounces twice loses the point. Scoring is very similar to volleyball. If the non-server player wins the point, then the serve switches but no score is made. Games are played to 15 points, and the winner must win by two. However, in tournament play, two games are played to 15 points in which you do not have to win by 2. If necessary, a third game, or "tie-breaker" is played to 11 points, again, with a one point margin of victory acceptable. In four player games, the two players on each side both serve before the sides switch.

Racquetball is a very fast moving game. Expert players are adept at precisely controlling the course of the ball, using unusual bounces off walls to confuse the opponent. A typical strategy for scoring is also to hit the ball so that is strikes as low as possible on the front wall. This causes the ball to bounce on the floor almost immediately after deflecting, making it difficult for the other player to respond in time.

There are many other types of shots. A ceiling shot hits high off the front wall and then hits the ceiling. This type of shot tends to float high above the players and strike the court floor near the back wall. Another type of shot is a Z-shot, where the ball bounces off of both side walls in a Z shape before hitting the front wall. The ball tends to drop very quickly when it hits the front wall and is very difficult to return.