En Passant

"En passant" is a special pawn capture rule in chess that allows a pawn to capture an opponent's pawn that has just moved two squares forward from its starting position, as if it had only moved one square forward. This capture can only occur on the very next move after the opponent's pawn has made the initial two-square move.

Here's how the en passant rule works:

When an opponent's pawn moves two squares forward from its starting position, and lands adjacent to your pawn, you have the option to capture it en passant on your next move.
You move your pawn diagonally to the square where the opponent's pawn would have landed if it had moved only one square forward. This captures the opponent's pawn as if it had moved one square forward, and you remove the captured pawn from the board.
It's important to note that the en passant capture must be executed immediately on the next move. If you fail to capture en passant on your next move, the opportunity is lost, and the game continues as usual.
En passant can also lead to a double check situation, where the opponent's king is in check from both your pawn and a checking piece (usually a queen, rook, or bishop). In such cases, the opponent's only legal option is to move the king.

En passant is a strategic element in the game that can affect pawn structures, piece development, and tactics. It serves to prevent pawns from advancing too quickly without the possibility of being challenged, and it adds an extra layer of complexity to pawn play and positioning.

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