For an abbreviated version of the squash rules, read on:
A match is the best of 5 games
Each game is to 15 points, unless the score reaches 14 – all at which stage the winner needs to win by two clear points.
Points are scored by whoever wins the rally; whoever wins the rally then becomes the server.
The player to serve first is decided by the spin of a racket. Each new game is started by the winner of the last.
Your first serve can be from either box, after winning a rally the server then continues serving from the alternate box (you only get 1 go at the serve, there are no second chances).
To serve you must have at least one foot on the floor within the service box (not touching the line). The serve must hit the front wall above the service (middle) line and below the out (top) line, to land (unless volleyed) within the back quarter of the court opposite to the server's box.
After the serve, the ball must hit the front wall, and can hit any wall on its way there.
The ball can only bounce once and must stay below the top line and above the 'Tin' at the bottom of the front wall.
LETS AND STROKES
If you think you are going to hit your opponent with the ball or the racket, DO NOT PLAY THE BALL, ask for a LET. If the ball could have gone to the front wall it is a STROKE (point or hand out). If the ball was going to the side wall first, a LET is played (play the point again). The same applies if you actually hit the ball and then your opponent, but for safety reasons it is better not to hit it!
If you TURN on the ball and hit your opponent it is considered a dangerous shot and you surrender a point or the serve. PLAY SAFE - Don't hit it.
If your opponent is seriously impeding your back swing or follow through, you receive aSTROKE. If they are attempting to get out of your way then play a LET.
In most cases if you get hit by the ball or a racket, it is your own fault and the point goes to your opponent because you are impeding their shot.
REMEMBER: PLAY SAFE, give your opponent plenty of room to play the ball, and call a LET if you think you are going to hit them.