I have never understood who serves first, and when it switches, in table tennis.
Could anyone explain it?
Table tennis serving rules have changed over the years. Under the current ITTF rules, the player to serve first is chosen at random, with the winner of the random draw able to choose to serve first or receive first. Sometimes in casual games, the first serve is chosen by volley, where a "practice" rally is played to determine who serves first.
The player who is serving changes after a certain number of points are scored. Under the current ITTF rules, in an 11 point game, the service changes every 2 points. In the past, when games were played up to 21 points, the service changed every 5 points.
Here is an example of how this works.
In an 11 point game, the game must be won by a 2-point lead. If both players score 10 points, the service switches after every point until the game is over.
The current ITTF rules for order of serving are found in the ITTF Handbook, section 2.13:
2.13 THE ORDER OF SERVING, RECEIVING AND ENDS
2.13.01 The right to choose the initial order of serving, receiving and ends shall be decided by lot and the winner may choose to serve or to receive first or to start at a particular end.
2.13.02 When one player or pair has chosen to serve or to receive first or to start at a particular end, the other player or pair shall have the other choice.
2.13.03 After each 2 points have been scored the receiving player or pair shall become the serving player or pair and so on until the end of the game, unless both players or pairs score 10 points or the expedite system is in operation, when the sequences of serving and receiving shall be the same but each player shall serve for only 1 point in turn.
2.13.04 In each game of a doubles match, the pair having the right to serve first shall choose which of them will do so and in the first game of a match the receiving pair shall decide which of them will receive first; in subsequent games of the match, the first server having been chosen, the first receiver shall be the player who served to him or her in the preceding game.
2.13.05 In doubles, at each change of service the previous receiver shall become the server and the partner of the previous server shall become the receiver.
2.13.06 The player or pair serving first in a game shall receive first in the next game of the match and in the last possible game of a doubles match the pair due to receive next shall change their order of receiving when first one pair scores 5 points.
2.13.07 The player or pair starting at one end in a game shall start at the other end in the next game of the match and in the last possible game of a match the players or pairs shall change ends when first one player or pair scores 5 points.