Zugzwang describes a chess situation where a player must make a move that worsens their position. The term comes from German "compulsion to move" and has specific meaning in combinatorial game theory, where a move directly changes a game's outcome from win to loss. Though the concept existed centuries before the term, it was recorded in German chess literature by 1858.

World Champion Emanuel Lasker introduced zugzwang to English chess literature in 1905. The concept appears in ancient studies dating back to the 9th century, including shatranj positions analyzed by Zairab Katai. Reciprocal zugzwang positions, where both players would be disadvantaged if it were their turn, prove crucial in endgame analysis according to experts like John Nunn.

Zugzwang most frequently occurs in chess endgames with limited pieces and moves. The simplest example shows how being forced to move can turn a winning position into a draw or loss. Players often use triangulation techniques to maneuver their opponent into zugzwang positions, demonstrating how understanding this strategic concept can determine game outcomes.