When there is only a single man on a point, it is called a "blot." When a blot is left, the man there may be taken up (technically the blot may be "hit") by the adversary if he throws a number which will enable him to place a man on that point. The man hit is placed on the bar, and has to begin again by entering the adversary's home table again at the next throw should it result in a number that corresponds to an unblocked point. The points in the home tables count for this purpose as 1, 2, 3, 4, 5, 6, beginning from the ace-point. A player is not allowed to move any other man while he has one to enter. It is, therefore, an advantage to have made all the points in your own board, so that your adversary, if you take a man up, cannot enter; and you can then continue throwing until a point is opened.
The game proceeds until one of the players gets all his men into his inner table or home. Then he begins to take his men off the board, or to bear them, i.e. to remove a man from any point that corresponds in number with his throw. If such a point is unoccupied, a move must be made, if there is room for it, and a move may be taken, instead of bearing a man, at any time; but when six is empty, if six is thrown a man may be borne from five and so on. If, after a player has commenced throwing off his men, he should be hit on a blot, he must enter on his adversary's inner table and must bring the man taken up into his own inner table before he can bear further.
Whoever first takes off all his men wins the game:—a single game (a "hit") if his adversary has begun bearing; a double game (a "gammon") if the adversary has not borne a man; and a triple game (a "backgammon") if, at the time the winner bears his last man, his adversary, not having borne a man, has one in the winner's inner table, or has a man up. When a series of games is played, the winner of a hit has the first throw in the succeeding game; but if a gammon is won, the players each throw a single die to determine the first move of the next game.
In order to play backgammon well, it is necessary to know all the chances on two dice and to apply them in various ways. The number of different throws that can be made is thirty-six. By taking all the combinations of these throws which include given numbers, it is easily discovered where blots may be left with the least probability of being hit. For example, to find the chance of being hit where a blot can only be taken up by an ace, the adversary may throw two aces, or ace in combination with any other number up to six, and he may throw each of these in two different ways, so that there are in all eleven ways in which an ace may be thrown. This, deducted from thirty-six (the total number of throws), leaves twenty-five; so that it is 25 to 11 against being hit on an ace. It is very important to bear in mind the chance of being hit on any number. The following table gives the odds against being hit on any number within the reach of one or two dice: -
| It is | 25 | to | 11, | or about | 9 | to | 4, | against being hit on | 1 |
| " | 24 | " | 12, | or | 2 | " | 1, | " | 2 |
| " | 22 | " | 14, | or about | 3 | " | 2, | " | 3 |
| " | 21 | " | 15, | or | 7 | " | 5, | " | 4 |
| " | 21 | " | 15, | " | 7 | " | 5, | " | 5 |
| " | 19 | " | 17, | " | 9½ | " | 8½, | " | 6 |
| " | 30 | " | 6, | " | 5 | " | 1, | " | 7 |
| " | 30 | " | 6, | " | 5 | " | 1, | " | 8 |
| " | 31 | " | 5, | or about | 6 | " | 1, | " | 9 |
| " | 33 | " | 3, | or | 11 | " | 1, | " | 10 |
| " | 34 | " | 2, | " | 17 | " | 1, | " | 11 |
| " | 33 | " | 3, | " | 11 | " | 1, | " | 12 |
The table shows that if a blot must be left within the reach of one die, the nearer it is left to the adversary's man the less probability there is of its being hit. Also, that it is long odds against being hit on a blot which is only to be reached with double dice, and that, in that case (on any number from 7 to 11), the farther off the blot is, the less chance there is of its being hit.
The table assumes that the board is open for every possible throw. If part of the throw is blocked by an intervening point being held by adverse men, the chance of being hit is less.
Two principles, then, have to be considered in moving the men:— (1) To make points where there is the best chance of obstructing the opponent. (2) When obliged to leave blots, to choose the position in which they are least likely to be hit.
The best points to secure are the five-point in your own inner table and the five-point in your adversary's inner table. The next best is your own bar-point; and the next best the four in your own inner table.
The best move for some throws at the commencement of a game is as follows:—Aces (the best of all throws), move two on your bar-point and two on your five-point. This throw is often given to inferior players by way of odds.