The first moves of a
backgammon game are the
opening moves, collectively referred to as the opening, and studied in the
backgammon opening theory. Backgammon opening theory is not developed in as much detail as
opening theory in chess, which has been widely studied. The reason for this is that following the first move in backgammon, there are 21 dice roll outcomes on each subsequent move, and many alternative plays for each outcome, making the
tree of possible positions in backgammon expand much more rapidly than in chess.