Backgammon
Backgammon is a two-player board game played on a board of twenty-four narrow triangular points. Each player controls fifteen checkers and moves them in opposing directions around the board, aiming to bring all fifteen into their home board and then remove them — a process called bearing off. The first player to bear off all fifteen checkers wins. Movement is determined by the roll of two dice; each die is a separate move, and while luck influences individual outcomes, the stronger player prevails consistently because sound positional decisions and accurate probability assessment outweigh short-term variance over any meaningful number of games.
The board
The board is divided lengthways into four quadrants of six points each. The two quadrants on your side of the board are your home board (points 1–6) and your outer board (points 7–12). The two quadrants on your opponent's side are their outer board (points 13–18) and their home board (points 19–24). Running down the centre of the board is a raised divider called the bar, which separates the two halves.
Points are numbered 1 to 24 from each player's perspective. In the examples on this page, white moves from point 24 toward point 1, and black moves from point 1 toward point 24 — in the opposite direction. This is just a convention for these diagrams; in a real game either player may move in either direction, agreed at the start. Because the numbering is relative to each player, white's point 1 is the same physical point as black's point 24, and vice versa.
Starting position
Each player's fifteen checkers are placed in the same pattern at the start of every game. Every other point starts empty. Because the two players move in opposite directions, the positions are mirror images of each other.
| Black — moves from point 1 → 24 | White — moves from point 24 → 1 | ||
|---|---|---|---|
| Point | Checkers | Point | Checkers |
| 1 | 2 | 24 | 2 |
| 12 | 5 | 13 | 5 |
| 17 | 3 | 8 | 3 |
| 19 | 5 | 6 | 5 |
How to play
- Beginning the game. Each player rolls one die. The player with the higher number moves first, using the two dice rolled between them as their opening move. If both dice show the same number, roll again. After this, players alternate turns, each rolling both dice at the start of their turn.
- Moving checkers. The two dice represent two separate moves. If you roll a 4 and a 2, you may move one checker four points and another checker two points, or you may move a single checker a total of six points — provided the intermediate point is also accessible (not blocked by two or more of your opponent's checkers). You must use both numbers if legally possible. If you can use one number but not both, you must use the larger one if that is possible.
- Doubles. Rolling the same number on both dice — for example, two 3s — entitles you to four moves of that number rather than two. A roll of double 3s gives four separate moves of three points each.
- Where you may land. You may land on any point that is unoccupied, occupied by your own checkers, or occupied by exactly one opposing checker. A point occupied by two or more of your checkers is called a made point — your opponent cannot land there under any circumstances.
- Hitting a blot. A single checker sitting alone on a point is called a blot. If you land on your opponent's blot, you hit it. The hit checker is removed from the board and placed on the bar. That player must re-enter from the bar before moving any other checker.
- Re-entering from the bar. A checker on the bar must re-enter before any other move can be made. On your turn you still roll both dice. Each die is a separate re-entry opportunity, so a 4 and a 6 mean the checker can re-enter on your opponent's 4-point or 6-point if that point is open. If one of the matching points is blocked by two or more of your opponent's checkers, you may still use the other die if it allows entry. If neither die can enter the bar checker, you lose the turn entirely. In the example below the dice are 6 and 4; the 6-point is blocked, so the checker re-enters on the open 4-point.
- Bearing off. Once all fifteen of your checkers are within your home board (points 1–6), you begin bearing off. Roll the dice and remove checkers from the matching points: a 4 removes a checker from the 4-point, a 2 from the 2-point, and so on. If you roll a number higher than your highest occupied point, you remove a checker from the highest occupied point. If a checker is hit while you are bearing off, it must re-enter the board and return to your home board before bearing off resumes.
The first board shows Black in a bearing-off position. The home quadrant is labelled 1–6, and the counters already borne off are shown as a side stack.
- Winning. The first player to bear off all fifteen checkers wins, scoring one point. If the losing player has not borne off any checkers, the winner scores a gammon, worth two points. If the losing player still has a checker on the bar or within the winner's home board, the winner scores a backgammon, worth three points.
Strategy
- Build made points. Two or more of your own checkers on a point make it permanently safe while they remain there — your opponent cannot land on it, though they can still move past it. Made points are the foundation of every strong position; a single checker on a point is always at risk.
- Secure the 5-point early. Your 5-point (and your opponent's 5-point, which from your perspective is the 20-point) are the two most valuable points on the board. Controlling your own 5-point blocks your opponent's back checkers from escaping cleanly; controlling their 5-point establishes a deep anchor in their home board.
- Build a prime. A sequence of six consecutive made points forms a prime — a barrier that the opposing checkers cannot cross by any single combination of dice. Trapping your opponent's checkers behind a five- or six-point prime while advancing your own is a decisive strategic advantage.
- Hit with purpose. Hitting a blot sends it back to the bar and disrupts your opponent's position, but it also leaves your checker exposed on that point until your next turn. Hit when you can cover the new blot on a subsequent roll, or when the board position already favours you heavily.
- Manage your back checkers. The two checkers you begin on your opponent's 24-point are the most difficult to advance. Leaving them there too long allows your opponent to build a prime in front of them. Running early with a large double is often correct; slotting forward aggressively when the position is open is also sound.
- Use the cube accurately. The correct threshold for offering a double is roughly when your winning probability exceeds 70–75%. The correct threshold for accepting is roughly when you win at least 25% of the time from that position. These are baseline figures; the gammon and backgammon threats in the position affect both thresholds significantly.
History
Backgammon is among the oldest known race-and-block games. Ancient boards have been excavated at Shahr-e Sukhteh in Iran and at sites across the ancient Near East, some predating 3000 BC. Earlier forms of the game spread across the Roman Empire under various names — the Romans played a version called Tabula — and by the medieval period it was widely played across Europe and the Islamic world under names including Nard and Tables. The name backgammon appears in English from the seventeenth century, most likely from the Welsh bach (small) and cammaun (battle).
The modern doubling cube was introduced in New York in the 1920s and fundamentally changed competitive play by adding a layer of probabilistic decision-making above the movement of the pieces. Backgammon enjoyed a significant revival in the 1970s, particularly in the United States, where it became associated with high-stakes social gambling. Computer analysis of the game accelerated from the 1990s onward; today's strongest programs — built on neural-network evaluation — analyse positions at a level well beyond any human player and have refined the theory of opening play, prime construction, and doubling decisions considerably.