Backgammon setup

Backgammon is a game for two players, played on a board consisting of twenty-four narrow triangles called points . The triangles alternate in color and are grouped into four quadrants of six triangles each. The quadrants are referred to as a player's home board and outer board , and the opponent's home board and outer board. The home and outer boards are separated from each other by a ridge down the center of the board called the bar .

Outer Board	Red's Home Board
Outer Board	White's Home Board
A board with the checkers in their initial position. An alternate arrangement is the reverse of the one shown here, with the home board on the left and the outer board on the right

The points are numbered for either player starting in that player's home board. The outermost point is the twenty-four point, which is also the opponent's one point. Each player has fifteen checkers of his own color. The initial arrangement of checkers is: two on each player's twenty-four point, five on each player's thirteen point, three on each player's eight point, and five on each player's six point.

Both players have their own pair of dice and a dice cup used for shaking. A doubling cube , with the numerals 2, 4, 8, 16, 32, and 64 on its faces, is used to keep track of the current stake of the game.

Object of the Game

The object of the game is for a player to move all of his checkers into his own home board and then bear them off. The first player to bear off all of his checkers wins the game.

Outer Board	Red's Home Board
Outer Board	White's Home Board
Direction of movement of White's checkers. Red's checkers move in the opposite direction.

Movement of the Checkers

To start the game, each player throws a single die. This determines both the player to go first and the numbers to be played. If equal numbers come up, then both players roll again until they roll different numbers. The player throwing the higher number now moves his checkers according to the numbers showing on both dice. After the first roll, the players throw two dice and alternate turns.

The roll of the dice indicates how many points, or pips , the player is to move his checkers. The checkers are always moved forward, to a lower-numbered point. The following rules apply:

1. A checker may be moved only to an open point , one that is not occupied by two or more opposing checkers.
2. The numbers on the two dice constitute separate moves. For example, if a player rolls 5 and 3, he may move one checker five spaces to an open point and another checker three spaces to an open point, or he may move the one checker a total of eight spaces to an open point, but only if the intermediate point (either three or five spaces from the starting point) is also open.

Outer Board	Red's Home Board
Outer Board	White's Home Board
Two ways that White can play a roll of 3,5

1. 3. A player who rolls doubles plays the numbers shown on the dice twice. A roll of 6 and 6 means that the player has four sixes to use, and he may move any combination of checkers he feels appropriate to complete this requirement.
2. 4. A player must use both numbers of a roll if this is legally possible (or all four numbers of a double). When only one number can be played, the player must play that number. Or if either number can be played but not both, the player must play the larger one. When neither number can be used, the player loses his turn. In the case of doubles, when all four numbers cannot be played, the player must play as many numbers as he can.

Hitting and Entering

A point occupied by a single checker of either color is called a blot . If an opposing checker lands on a blot, the blot is hit and placed on the bar .

Any time a player has one or more checkers on the bar, his first obligation is to enter those checker(s) into the opposing home board. A checker is entered by moving it to an open point corresponding to one of the numbers on the rolled dice.

For example, if a player rolls 4 and 6, he may enter a checker onto either the opponent's four point or six point, so long as the prospective point is not occupied by two or more of the opponent's checkers.

Outer Board	Red's Home Board
Outer Board	White's Home Board
If White rolls 6,4 with a checker on the bar, he must enter the checker onto Red's four point since Red's six point is not open.

If neither of the points is open, the player loses his turn. If a player is able to enter some but not all of his checkers, he must enter as many as he can and then forfeit the remainder of his turn.

After the last of a player's checkers has been entered, any unused numbers on the dice must be played, by moving either the checker that was entered or a different checker.

Bearing Off

Once a player has moved all of his fifteen checkers into his home board, he may commence bearing off . A player bears off a checker by rolling a number that corresponds to the point on which the checker resides, and then removing that checker from the board. Thus, rolling a 6 permits the player to remove a checker from the six point.

If there is no checker on the point indicated by the roll, the player must make a legal move using a checker on a higher-numbered point. If there are no checkers on higher-numbered points, the player is permitted (and required) to remove a checker from the highest point on which one of his checkers resides. A player is under no obligation to bear off if he can make an otherwise legal move.

Outer Board	Red's Home Board
Outer Board	White's Home Board
White rolls 6,4 and bears off two checkers.

A player must have all of his active checkers in his home board in order to bear off. If a checker is hit during the bear-off process, the player must bring that checker back to his home board before continuing to bear off. The first player to bear off all fifteen checkers wins the game.

Doubling

Backgammon is played for an agreed stake per point. Each game starts at one point. During the course of the game, a player who feels he has a sufficient advantage may propose doubling the stakes. He may do this only at the start of his own turn and before he has rolled the dice.

A player who is offered a double may refuse , in which case he concedes the game and pays one point. Otherwise, he must accept the double and play on for the new higher stakes. A player who accepts a double becomes the owner of the cube and only he may make the next double.

Subsequent doubles in the same game are called redoubles . If a player refuses a redouble, he must pay the number of points that were at stake prior to the redouble. Otherwise, he becomes the new owner of the cube and the game continues at twice the previous stakes. There is no limit to the number of redoubles in a game.

Gammons and Backgammons

At the end of the game, if the losing player has borne off at least one checker, he loses only the value showing on the doubling cube (one point, if there have been no doubles). However, if the loser has not borne off any of his checkers, he is gammoned and loses twice the value of the doubling cube. Or, worse, if the loser has not borne off any of his checkers and still has a checker on the bar or in the winner's home board, he is backgammoned and loses three times the value of the doubling cube.

Optional Rules

The following optional rules are in widespread use.

1. Automatic doubles. If identical numbers are thrown on the first roll, the stakes are doubled. The doubling cube is turned to 2 and remains in the middle. Players usually agree to limit the number of automatic doubles to one per game.
2. Beavers. When a player is doubled, he may immediately redouble (beaver) while retaining possession of the cube. The original doubler has the option of accepting or refusing as with a normal double.
3. The Jacoby Rule. Gammons and backgammons count only as a single game if neither player has offered a double during the course of the game. This rule speeds up play by eliminating situations where a player avoids doubling so he can play on for a gammon.

Irregularities

1. The dice must be rolled together and land flat on the surface of the right-hand section of the board. The player must reroll both dice if a die lands outside the right-hand board, or lands on a checker, or does not land flat.
2. A turn is completed when the player picks up his dice. If the play is incomplete or otherwise illegal, the opponent has the option of accepting the play as made or of requiring the player to make a legal play. A play is deemed to have been accepted as made when the opponent rolls his dice or offers a double to start his own turn.
3. If a player rolls before his opponent has completed his turn by picking up the dice, the player's roll is voided. This rule is generally waived any time a play is forced or when there is no further contact between the opposing forces.

Basic Strategy

Backgammon is a race to see who bears off all of his checkers first. However, to play backgammon well requires strategy and an understanding of the components of a winning game plan. Here are some ideas to keep in mind when trying to determine the best strategy for a particular backgammon situation.

Anchoring

Anchoring is establishing a defensive point (anchor) in your enemy's home board. This gives you a landing spot to come in on should you get hit and prevents your opponent from making his home board. Early in the game try to establish anchors on the higher points (20,21). If you become significantly behind in the race, the lower points (22,23,24) have more value as your strategy is to build your home board and wait for a shot. If you have two anchors try to keep them on adjacent points. A technique that is often used to bring checkers in to act as anchors is re-circulating. Re-circulating refers to intentionally allowing a blot to be hit for the purpose of gaining time to preserve other valuable points.

Try to build points without gaps between them (a blockade) directly in front of the enemy checkers in your home board to prevent their escape. Six points in a row is called a prime. A prime makes it impossible for your opponent to escape for as long as you can maintain that structure. Six points in a row in the player's home board is called a "closed board" since any opposing checkers on the bar cannot legally re-entered and are close or shut out of the game until the controlling player uncovers on the six points. Consider shifting points (giving up one point in order to make an adjacent point) if it helps to create a blockade.

Communication is a distribution of checkers so that they kept within six pips of one another. This ensures that a checker will be nearby if a man needs to be covered or if a runner needs a point to rest at.

Distribution is how evenly your checkers are divided among the points occupied. It is usually better to have 3 checkers each on two different points rather than 4 checkers one and 2 on the other. You should rarely have six checkers on a point and almost never have any more. A player with even distribution will have more flexibility to use his rolls to his advantage than a player that has five or six checkers stacked up on a single point.

Diversification is the spreading out of a player's checkers to increase the number of good rolls on a subsequent turn.

Duplication refers to a technique for reducing the number of good rolls for the opponent. A player places his checkers so that two of the opponent's desired moves in different parts of the board both require the same die value. For example: When a player must leave two blots exposed to direct shots, it is best to place them the same number of pips away from their respective attacking points. When the opponent has a checker on the bar and a player must leave a blot exposed to a direct shot, it is best to leave a shot that uses the same die value as one the opponent needs to enter his checker.

It is sometimes good strategy to leave blots early in the game so that they can be used to establish a strong offense or defense. These blots are often called slots. Slots are a single checkers that are left exposed on a point the player wishes to make, with the intention of covering the blot on the next turn. However, if you are in a weaker position consider consolidating. Consolidating refers to reducing your number of blots.

Try to hit checkers that are the most advanced or checkers that your opponent would like to cover to establish an important point. Attack only when it is advantageous to do so. For example, if you already have two enemy checkers on the bar, it is more critical to make another point in your home board than to hit a third checker. Also refrain from hitting if it makes you more vulnerable than your opponent. If possible hit and cover, rather than hit loose, in order to avoid leaving the player's own blots in danger of a return hit. Also keep the power of the potential for hitting in mind. Keeping checkers within hitting distance of a point held by only two of the opponent's checkers will "freeze the opponents builders" by restricting these checkers from being active builders. Similarly, if it is not advantageous to hit your opponent's blot you can alternatively apply pressure by using a checker so that it directly bears on the opponent's blot, forcing the opponent to cover the blot, move it, rather than use his turn to make a point.