The Doubling Cube

Backgammon was completely modified when, at the beginning of the 20th century, the notion of doubling was introduced. Prior to the beginning of the game, the doubling cube with the number 64 facing up is put beside the board, which means that only one point or unit are being played for. If a player feels lucky and wants to double the stakes of the game, he can do so by rotating the cube so that the 2 is on top.

Each player is allowed to double the stakes only on his or her own turn and only prior to throwing the dice. If the opponent feels unlucky, he or she may decide, when his or her turn comes up, to reject the double. Either player is allowed to make the first double, but when a player accepts a double, he is considered the "owner of the cube", which means that only he can re-double the stakes. He can do so as many times as he wishes, but typically no one redoubles more than four times.

The Crawford Rule

According to this customary rule, if the leader gets to be only one point away from winning, the pursuing player is not allowed to make a double for the rest of the game. The reason for this is that the pursuing player may decide to double the stakes every round of the game. He has nothing to lose by doing so, since there is no significance to the number of points he loses by. Therefore, the leader gets a chance to finish the match by having one undoubled game.