Section 5: Rules of Play

A rally is the sequence of playing actions from the moment of the service hit by the server up to the moment the ball is out of play (Rule 11.1). If the serving team wins a rally, it scores a point and continues to serve.

Source: Rule 11, Rule 11.1, Rule 11.2, Rule 11.3.1, Rule 11.3.2, Rule 12, Rule 12.1, Rule 12.2, Rule 12.3, Rule 12.4, Rule 13, Rule 13.1, Rule 13.2.1, Rule 13.2.2, Rule 13.2.3, Rule 14, Rule 14.1, Rule 14.2, Rule 14.3, Rule 14.4

Send this to your friend — argument over.