In doubles, if the serving side wins a rally, the same player continues to serve, but he/she changes service courts so that she/he serves to a different opponent each time. If the opponents win the rally and their new score is even, the player in the right service court serves; if odd, the player in the leftservice court serves. The players' service courts are determined by their positions at the start of the previous rally, not by where they were standing at the end of the rally. A consequence of this system is that each time a side regains the service, the server will be the player who did notserve last time.ScoringMain article: Scoring system development of badmintonEach game is played to 21 points, with players scoring a point whenever theywin a rally regardless of whether they served(this differs from the old system where players could only win a point on their serve and each game was played to 15 points). A match is the best of three games.If the score reaches 20-all, then the game continues until one side gains a two-point lead (such as 24–22), except when there is a tie at 29-all, in which the game goes to a golden point. Whoever scores this point will win.At the start of a match, the shuttlecock is cast and the side towards which the shuttlecock is pointing serves first. Alternatively, a coin may be tossed, with the winners choosing whether to serve or receive first, or choosing which end of the court to occupy first, and their opponents making the leftover the remaining choice.In subsequent games, the winners of the previous game serve first. Matches are best out of three: a player or pair must win two games (of 21 points each) to win the match. For the first rally of any doubles game, the serving pair may decide who serves and the receiving pair may decide who receives.The players change ends at the start of the second game; if the match reaches a third game, they change ends both at the start of the game and when the leading player's or pair's score reaches 11 points.LetsIf a let is called, the rally is stopped and replayed with no change to the score. Lets may occur because of some unexpected disturbance such as a shuttlecock landing on a court (having been hit there by players playing in
adjacent court) or in small halls the shuttle may touch an overhead rail whichcan be classed as a let.If the receiver is not ready when the service is delivered, a let shall be called;yet, if the receiver attempts to return the shuttlecock, the receiver shall be judged to have been ready.EquipmentBadminton racquetsBadminton rules restrict the design and size of racquets and shuttlecocks.RacquetsBadminton racquetsare lightweight, with top quality racquets weighing between 70 and 95 grams (2.5 and 3.4 ounces) not including grip or strings.