Checkmate or stalemate? Ask these two questions
Distinguish a win from a draw by checking the king's safety and every available legal move.
First ask whether the king is in check
Check means that the king is under attack. The player to move must remove that attack legally. They might move the king, capture the checking piece, or block a line of attack. A knight's check cannot be blocked because a knight jumps; it must be answered another way.
Checkmate means the king is in check and the player has no legal response. A king with no empty neighbouring square is not necessarily mated. Another piece may capture the attacker or interpose. Start with the check, then examine all legal ways to answer it.
Then ask whether any legal move exists
Stalemate means the player to move is not in check and has no legal move with any piece. It is a draw. The distinction is about the entire position, not just the king. If a pawn can advance legally, or a rook can move, the position is not stalemate even if the king is boxed in.
Consider a black king on h8, a white king on f7, and a white queen on g6, with Black to move and no other pieces. The black king is not in check. It cannot move to g8, g7, or h7 because those squares are controlled. With no other legal move, that position is stalemate, not a win for White.
Keep an escape square until the final check
When winning with a queen, use your king to help restrict the opponent's king, but check for stalemate before making a quiet queen move. Moving the queen close to the edge can remove the last legal square without giving check. Capturing the opponent's final pawn can create the same problem.
A safe finishing method is to make purposeful checks and coordinate the king rather than repeatedly shrinking the opponent's space without inspecting their legal moves. Do not rely on a memorised picture alone. A king one square away, or a remaining pawn on a different file, can change the result.
Read the result before starting the review
ChessNexa distinguishes checkmate from drawn endings in the result message. A game can also end before checkmate through resignation, an agreed draw, or a clock result. The number of pieces remaining is therefore not enough to explain why a popup appeared; read its stated reason and the displayed clocks.
For practice, take a queen ending from your history and stop before the final move. Count the defender's legal moves, then replay the move and count again. You are trying to recognise what changed: an attack on the king, the loss of an escape square, or the removal of the final movable piece.
Put it into practice
Play a game on ChessNexa, then use the move history to review one moment where this idea mattered. You can also try a mate-in-one puzzle in the Puzzles tab.