Special Chess Moves

Castling is the only move where you move two pieces at once — the king and one rook — and it is the main way to get your king to safety. The king moves two squares toward a rook, and that rook jumps to the square the king crossed.

You may castle only if all of these are true:

• Neither the king nor that rook has moved yet.
• There are no pieces between them.
• The king is not in check, and does not pass through or land on an attacked square.

Castling toward the nearer rook is "kingside" (short); toward the far rook is "queenside" (long).

En passant ("in passing") is a special pawn capture. If your opponent advances a pawn two squares from its starting position and it lands directly beside one of your pawns, you may capture it as if it had moved only one square — but only on your very next move. Miss the chance and the right is gone.

When a pawn reaches the far end of the board (the 8th rank for White, the 1st for Black) it must immediately be promoted to a queen, rook, bishop or knight of the same colour. Almost everyone chooses a queen (the strongest piece), but occasionally a knight is better — this is called underpromotion. Promotion can give you a second (or third) queen.