A player is in zugzwang if he is to move yet every move significantly worsens the position. Literally, zugzwang means forced move, from the German words Zug (move) and Zwang (force). Zugzwang positions typically arise in endings, but they can also occur in middle games. A deep understanding of zugzwang is crucial to strong ending play.
White: Kb4, Nb3, Bd3, a5, e3, f3, g3, h2.
Black (to move): Kd6, Ne6, Bc8, a6, d5, f7, g6, h7.
White: Kd4, Bb5, b2, e3, f4, g5.
Black (to move): Kd6, Bc8, a5, d5, f7, g6.
White (to move): Kg1, Re4, Bg2, a2, b2, c2, f4, g3, h2.
Black: Kd7, Rh8, Nf6, a6, b7, c5, f7, g7, h6.
White: Kh1, Qd4, Rb1, Ng4, a4, c4, g2, h2.
Black (to move): Kf8, Qg8, Re7, Ne4, a6, f5, g6, h7.