En Passant

In chess, en passant "in passing" describes the capture by a pawn of an enemy pawn on the same rank and an adjacent file that has just made an initial two-square advance. The capturing pawn moves to the square that the enemy pawn passed over, as if the enemy pawn had advanced only one square. The rule ensures that a pawn cannot use its two-square move to safely skip past an enemy pawn.Capturing en passant is permitted only on the turn immediately after the two-square advance; it cannot be done on a later turn. The capturing move is sometimes notated by appending the abbreviation e.p.