Smothered mate
A knight mates a king that is boxed in by its own pieces.
Knight to f7 is mate. The king on h8 is surrounded by its own rook and pawns, and nothing can take the knight.
The famous version, Philidor’s legacy, uses a queen sacrifice to force the rook onto g8 first.
New to chess? The examples here use it. Play your first moves (five minutes), then learn chess from the beginning, one short lesson at a time.
Want more? Puzzles on this from real games, on Lichess, free and with no account. They are not counted in your progress here.