Checkmate is when a king is in check and has no legal way to escape — it ends the game immediately, and the side delivering it wins.
Checkmate is the object of the game. It happens when a king is attacked (in check) and there is no legal move to answer it: the king can't move to safety, the check can't be blocked, and the checking piece can't be captured.
The king is never actually captured in chess — the game ends the instant a position is mate. Checkmate is written with ‘#’ after the move (for example Ra8#).
A huge share of club games end with the king still in the centre or stuck behind its own pawns. The back-rank mate, where a rook or queen delivers mate along the first rank while the king is hemmed in by its own pawns, is one of the most common patterns of all.
Check means the king is attacked but can still escape. Checkmate means the king is attacked and has no legal escape — and the game ends right there.
A checkmate delivered by a rook or queen along the king's back rank, when the king is trapped by its own unmoved pawns and has no flight square.
BetterChess is a practice tool — we make no guarantee you'll reach 1800 or any rating. Definitions are standard chess terminology; every diagram position is checked legal with the same engine the board runs.