Squash scoring systems have evolved over time. The original scoring system is known as English scoring, also called hand-out scoring. Under this system, if the server wins a rally, they receive a point, while if the returner wins the rally, only the service changes (i.e., the ball goes "hand-out") and no point is given. The first player to reach 9 points wins the game. However, if the score reaches 8-8, the player who was first to reach 8 decides whether the game will be played to 9, as before (called "set one"), or to 10 (called "set two"). At one time this scoring system was preferred in Britain, and also among countries with traditional British ties, such as Australia, Canada, Pakistan, South Africa and India.
See http://en.wikipedia.org/wiki/Squash_(sport) for more information.