This article is from the Table Tennis (Ping Pong) FAQ, by ttennis@bu.edu with numerous contributions by others.
7.1 At the start of service, the ball shall rest freely on the open,
flat palm of the free hand and shall be stationary, above the level
of the playing surface, and behind the server's end line.
7.2 The ball and the racquet shall be above the level of the playing
surface and behind the end line of the server's court or an
imaginary extension thereof from the last moment at which the ball
is stationary on the palm of the free hand until the ball is struck
in service.
7.3 The server shall then project the ball near vertically upwards, by
hand only and without imparting spin, so that it rises at least 6
inches after leaving the palm of the hand.
7.4 As the ball is then descending from the height of its trajectory,
the server shall strike it so that it touches first his own court
and then, passing directly over the net or around or under the
projection of the net and its supports outside the table, touches
the receiver's court.
7.4.1 In doubles, the points of contact of the ball with the playing
surface shall be the server's right hand court and then the
receiver's right hand court.
7.4.2 If, in attempting to serve, a player fails to strike the ball while
it is in play, he shall lose a point.
7.5 When the ball is struck in service, it shall be behind the end line
of the server's court or an imaginary extension thereof, but not
farther back than the part of the server's body, other than his
arms, leg or head, which is farthest from the net.
7.6 It is the responsibility of the player to serve so that the umpire
or assistant umpire can see that he complies with the requirements
for a good service.
7.6.1 If the umpire is doubtful about the correctness of a player's
service but neither he nor the assistant umpire is sure it is
illegal, he may on the first occasion in a match interrupt play and
warn the server without awarding a point.
On any subsequent occasion in the same match at which the same
player's service is of doubtful correctness, for the same or any
other reason, the player shall not be given the benefit of the
doubt and shall lose a point.
7.6.2 Where, however, there is a clear failure to comply with the
requirements for a good service no warning should be given and a
point should be awarded against the server.
7.7 Exceptionally strict observance of the prescribed method of service
may be waived where the umpire is notified, before play begins,
that compliance is prevented by physical disability.
 
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