En Passant in Chess: 

It is a unique technique of pawn capturing. It is a special rule for chess.
We know a pawn can move one square in its first move. Pawn always move straight forward and it never move backward. Pawn can naturally take the pieces diagonally.


Here some rules apply for en passant.
1.  The capture pieces of pawn must be on its fifth rank.
2.  The capturing pawn must be moved two soiree from its starting position.

example of en passant


Origin of En Passant in chess:

En passant origin in Europe in the fifteen century, where modern rule of chess developed. But before that period pawn was moved just one square forward at a beginning of its first move. Finally pawn moves modify and it moves two square in its beginning move if the player want.