On a wooden board marked with a simple grid, two players take turns setting down smooth stones, one side black and the other white. There are no dice, no cards, and no hidden information. Each stone is identical to every other stone of its color, and once placed, a stone never moves again unless it is captured and lifted from the board. A player claims territory by surrounding empty points with stones, captures enemy stones by surrounding them, and at the end counts the ground held. That is nearly the whole of the game.

Players take turns placing stones on the intersections of the grid, not inside the squares, and the object is to control more of the board's territory than the opponent. A player claims vacant intersections by surrounding them, and at the end each side counts the empty points it has enclosed, along with the enemy stones it has captured. Every stone or connected group of stones has liberties, the empty points directly adjacent to it, and a group survives only so long as it keeps at least one liberty. If a player fills the last liberty of an enemy group and surrounds it, the opponent’s group is captured and lifted from the board. Thus, the fundamental struggle of Go is the effort to build groups that cannot be surrounded, while threatening to surround and eliminate the groups of the opponent.

The heart of the game lies in the idea of life and death. A group achieves unconditional life by enclosing two separate internal spaces, called eyes, because the opponent cannot fill two points at once and thus can never take the group's final liberties. Much of the tactical drama of a game turns on whether a group can make two eyes and live or can be denied the eyes and eliminated. A special rule called the ko governs a position in which a single capture could otherwise repeat indefinitely, forbidding an immediate recapture and forcing a player to make a threat elsewhere first, thereby introducing a subtle currency of exchange into the fight.