In the Laws of Table Tennis, Law 2.6.1 states
2.6.1 Service shall start with the ball resting freely on the open palm of the server's stationary free hand.
In the accompanying photograph, you can see a number of incorrect methods of holding the ball prior to starting the toss.
- The top right method is illegal, since the ball is resting on the fingers of the free hand, not the open palm.
- The bottom left method is illegal, since the ball is being held in the fingers themselves.
- The bottom right method is illegal, since the palm is not open, but cupped. The ball is not resting freely, but is held in place by the fingers and bottom of the palm.
- The top left method is legal, since the palm is open and flat, allowing the ball to rest freely. Note that even though the thumb is over the table, the ball is still held behind the endline - so this does not make the serve illegal (I will explain this in more detail later).
The free hand must also be stationary when beginning the serve, so it is illegal for a player to pick up the ball and throw it into the air for service, without pausing to hold the free hand stationary before tossing the ball.
Video - Explanation of Law 2.6.1 - 5MB, 640x480 pixels
Video - Can You Serve With Your Hand Over the Table? - 2.9MB, 640x480 pixels