The Service Zone
If you are facing the front wall, then you'll see in the middle of a racquetball court the service zone. The service zone has two horizontal lines that are unbroken that are 5 feet apart. There are also four vertical lines inside this area that break the zone into five boxes. There are two small boxes on each side and one large box in the middle.
The person who is serving must stand in the large box in the middle of the serving zone. The person who is receiving the ball will stand close to the back wall because that is where the ball is likely going after it has been served. The smaller boxes in the serving zone are not used in a singles game of racquetball. Those boxes are where teammates stand during the serve in a doubles game.
There are many rules that apply when serving in racquetball. The ball must be bounced on the ground one time and then hit by the server. The ball must hit the front wall before it hits anything else. The ball may hit a side wall after it hits the front wall, but it can't hit both side walls or one side wall and a ceiling; it must only hit two surfaces before hitting the ground. Once the ball has bounced off of the walls and it lands on the ground, it must at least go behind the front line of the service zone. Failing to follow any of these rules results in a sideout.
Returning the Serve
After the ball hits the ground once, the receiver must hit the ball before it bounces a second time. To return the serve successfully, the return must hit the front wall. It is OK if the return hits the side wall or the ceiling before it hits the front wall. It just has to hit the front wall before the ball hits the ground.
Aces and Sideouts
Serving in racquetball is similar to volleyball. Only the player serving can score a point. If the server hits a legal serve and the opponent is not able to return it, then that is an ace. If the server gets an ace or wins the rally following the serve, then the server receivers a point and he gets to keep on serving as long as he keeps scoring. If the server fails to serve correctly, then that is a sideout. If the server gets a sideout or the receiver wins the rally after the serve, then the receiver will not gain a point. Instead, the receiver will get the right to serve next.