A mistake makes your position worse, while a blunder is usually a much more serious error that can lose material, the position, or even the game.

A zugzwang happens when a player would prefer to pass, but must move—and that required move makes their position worse.

Stalemate happens when the player to move has no legal move but their king is not in check. The result is a draw.

Yes, a pawn can become a queen through promotion, but a queen is not the only piece a pawn can become.

En passant is a special pawn capture that can happen immediately after an opponent advances a pawn two squares from its starting position.

A discovered check reveals an attack from another piece, while a double check means the king is attacked by two pieces at the same time.

A discovered check happens when one piece moves away and reveals another piece’s attack on the opponent’s king.

A rook check can sometimes be blocked when there are squares between the rook and the king. Learn how to spot the blocking opportunity.

A bishop check can sometimes be blocked, but only when there is at least one square between the bishop and the king.

A king can capture a checking piece only if the destination square is not attacked by another enemy piece.

You cannot block a pawn check because pawns attack diagonally onto adjacent squares. Learn how to respond when a pawn checks your king.

You cannot block a knight check because knights jump directly to their target squares. Learn how to respond when a knight attacks your king.

You can sometimes capture the piece giving check, but the capture must leave your king safe. Learn when this response is legal and when it fails.

Not sure whether castling is legal? Use this simple checklist to check every condition before making the move.

Check means the king is under attack but has a legal escape. Checkmate means the king is in check with no legal way to escape.

Being in check does not always mean the king has to move. Learn the three ways a player can legally respond to check.

A king can capture an opposing piece only if the destination square is not protected by another enemy piece.

Moving your king even once permanently removes your castling rights, even if the king later returns to its original square.

Moving your king even once permanently removes your castling rights, even if the king later returns to its original square.

Being in check earlier does not automatically remove your castling rights. Learn when you can still castle, what happens if your king moved, and which squares must be safe.

You cannot castle through check. Learn which squares the king must avoid, why the rule exists, and how to tell when castling is legal.

Can you castle if your rook is under attack? Yes, you can — an attacked rook doesn’t automatically prevent castling. What actually matters is whether the king is in a position that satisfies the castling conditions; an opponent merely attacking your rook doesn’t, by itself, change that. Why the Rook Being Attacked Doesn’t Stop Castling…