What is Zugzwang?

Zugzwang (German: "compulsion to move" ) is a position in which the player whose turn it is to move is at a disadvantage precisely because they must move—any move worsens their position. The player would prefer to pass if allowed. Zugzwang occurs most frequently in the endgame, particularly king and pawn endings. Types include:\n• Absolute zugzwang — any move results in immediate, decisive disadvantage.\n• Relative zugzwang — available moves are inferior but not immediately losing.\n• Mutual (reciprocal) zugzwang — whichever side moves is disadvantaged. A trebuchet is an extreme mutual zugzwang where the side to move loses.\n\nThe concept predates the term by centuries, appearing in shatranj studies from the 9th century. The term was first used in German chess literature around 1858 and entered English in 1905. The game Sämisch–Nimzowitsch, Copenhagen 1923, is known as the "Immortal Zugzwang Game."