service box
Noun
Meaning
A form of expansion joint used in street mains of steam-heating systems.
(squash, racquetball) One of two sections of the court, inside which a server must have at least one foot during the service
Source: en.wiktionary.orgExamples
A fault is a serve that falls long or wide of the service box, or does not clear the net.
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.
For a legal serve, one of the server's feet must be touching the service box, not touching any part of the service box lines, as the player strikes the ball.
The "service box" is formed by the short line (a solid red line running the court's width parallel to the front and back walls at a distance of 20 feet) and the service line (which runs parallel to the short line and is 15 feet from the front wall).
In a legal service, the ball travels over the net (without touching it) and into the diagonally opposite service box.
This player starts the first rally by electing to serve from either the left or right service box.