Checkmate and stalemate: no moves does not always mean victory
Your opponent cannot move, yet the game ends in a draw: a familiar beginner's surprise. Distinguish checkmate from stalemate. In both cases the side has no legal move, but one question decides the outcome: is its king in check right now?
Check for check first
Check means an enemy piece attacks the king. The attack must be removed by moving away, capturing the attacker or blocking its line, where possible. In checkmate no legal reply helps. The king is never removed: the game ends first. Do not declare mate merely because the king has little space; another piece may provide a defence.
Why the rook move is mate
Black's king is on h8, with pawns on g7 and h7. White plays d2–d8, attacking the king along the eighth rank. The rook also controls g8, while Black's own pawns occupy g7 and h7. Neither pawn can block the rook's line to the king, and no piece can capture the rook. This is checkmate, not just a strong check.
How stalemate happens
Consider Black's king on h8, White's queen on f7 and king on g6, with Black to move. The h8 king is not attacked. But the queen controls g8 and h7, and White's pieces control g7. There are no other black pieces, so no legal moves: stalemate and a draw. With an extra queen, a common mistake is removing the king's last square without check and forgetting to test legal replies.
Finish carefully
Before the decisive move, identify the check and possible replies: escape, capture or block. If there will be no check, find at least one legal opposing move before restricting space further. Replay the mate and try “Back-rank mate”. In a bot game, explain the final outcome in words. Understanding the finish is more useful than waiting for a victory message.
Your move now.
Practise the idea on the board. You can make mistakes, try again and start over.
Open exerciseRules and sources
Use these links to check the rules and explore the topic further.