Lesson
White to move. Main line: 1. Qd8#
Qd8 covers the whole back rank, and the white king on g6 covers g7 and h7 — every square around the black king is controlled by exactly one white piece.
The pattern to learn: the queen mates along the edge while the king stands one knight’s-move away, guarding the escape diagonal. Master this and no endgame with a queen up ever slips away.
The one thing to watch for is stalemate. Bring the queen too close without giving check — Qf7 here — and Black has no legal move and is not in check: the win evaporates on the spot. Before every quiet queen move, confirm the enemy king still has a square, or that you are checking.