SERVICE Rules to Remember...
Excerpts from the USTA Official Rules of Tennis and the USTA Code of Tennis
• The Server shall not serve until the Receiver is ready. If the Receiver attempts to return the service, they will be deemed ready and the point will be scored as played.

• May the Server hit the serve just as the Receiver looks up after
getting into the ready position? No. The Receiver is not ready until
the Receiver is in the ready position AND has a second or two to
make eye contact with the Server.

• Once ready, can the Receiver become unready? No. The Receiver
cannot become unready unless outside interference occurs.
Second serve interruptions? The Server is entitled to two serves if there is interruption DURING DELIVERY of the second serve.

When to serve? The receiver must be given adequate time to get into the ready position AND a second or two to make eye contact BEFORE the server may start the service motion.

A ball rolls on the court BETWEEN the first and second serve? Only if the time to clear the intruding ball is considered a prolonged interruption does the Server get two serves. The Receiver is the judge of whether it’s a sufficiently prolonged interruption.

A DELAY between the first and second serve? (Delay: broken string, contact lens problem, etc.) Delayed caused by Receiver ...two serves. Delay caused by Server ...one serve.
MAKING LINE CALLS

THE SERVE: The Receiver’s Partner should call the service line, and the Receiver should call the sideline and the center service line. Nonetheless, either partner may call a ball that either sees clearly.

IN THE MATCH: Opponent gets benefit of doubt. Players are guided by the unwritten law that any doubt must be resolved in favor of the opponent. A player in attempting to be scrupulously honest on line calls frequently will find themselves keeping a ball in play that might have been out or that the player discovers too late was out. Even so, the game is much better played this way.
MAKING CALLS DURING SERVICE...

Service calls by serving team. Neither the Server nor Server’s partner shall make a fault call on the first service even if they think it is out because the Receiver may be giving the Server the benefit of the doubt. But the Server and the Server’s partner SHALL CALL OUT any second serve that either clearly sees out.

Obvious faults. A player SHALL NOT PUT INTO PLAY or HIT over the net any obvious fault. To do so constitutes rudeness and may even be a form of gamesmanship.