Lesson
White to move. Main line: 1. f8=Q#
f8=Q is mate on arrival: the new queen checks along the eighth rank, the white king covers g7, and the rook on a7 covers h7 — the black king has nowhere to go and nothing can block.
When you push a passed pawn, look at what will control the king’s escape squares — a well-supported promotion often ends the game on the spot instead of merely winning material.
Promotion is also where stalemate lurks. A new queen can take the last square from a bare king, so if the position after promoting leaves the enemy with no move and no check, promote to a rook instead — or to a knight when a knight’s check is what the position actually needs.