Lesson
White to move. Main line: 1. Kf4 Re7 2. Qa6 Rd7 3. Qa5+ Ke8 4. Qb5 Ke7
The rook stays glued to its king, because a rook alone on an open board is picked off by checks and forks. So White cannot win it by attacking it — the king has to be forced away from it instead.
The method is zugzwang. White improves the king, then takes squares from the defenders with the queen, until Black runs out of moves that keep the rook protected. Every queen move here does one of those two jobs.
The tablebase rates this as a win in 47 moves with perfect play, which is the honest number: it is a technique to know, not a trick to spot. Over the board it is also why the fifty-move rule matters — the win exists, but only for a player who knows the method.