What is the two-bounce rule?

The serve and the return of serve must each bounce before being hit (Rule 10.A):

1. The receiver must let the serve bounce.
2. The serving team must let the return of serve bounce.

Hitting either one out of the air is a fault against the team that hit it. After those two bounces, players may volley or play off the bounce, subject to the kitchen rules.

A ball must always be returned before it bounces a second time (Rule 10.B).