As in indoor volleyball, the object of the game is to send the ball over the net in order to ground it on the opponent’s court, and to prevent the same effort by the opponent. A team is allowed up to three touches to return the ball. The ball is put in play with a service—a hit by the server from behind the rear court boundary over the net to the opponents. The rally continues until the ball is grounded on the playing court, goes “out”, or is not returned properly.
The team winning a rally scores a point (Rally Point System), and serves to start the following rally. The four players serve in the same sequence throughout the match, changing server each time a rally is won by the receiving team.
Reference: Wikipedia Beach Volleyball