board game of great antiquity, most popular in Europe during the 14th century and played throughout the world in various forms.

The board is made up of three concentric squares and several transversals, making 24 points of intersection. In modern play the diagonal lines of the board are usually omitted. Two players, each provided with nine counters of a single colour, lay pieces alternately upon the points, the object being to get three in a row (a mill) upon any line. On doing so, the player is entitled to remove from the board (capture) one adverse counter, but not one that is in a mill. Having placed all their counters, the players continue moving alternately, with the same object. A mill may be opened by moving one piece off the line; returning the same piece to its original position counts as a new mill. The player who captures all but two of the adverse pieces wins. A move is normally from one point to the next in either direction along a line, but the rule is sometimes made that, when a player has only three pieces left, he may move them from any point to any point regardless of the lines.