Discovered check is a chess term that refers to a type of check. Discovered check occurs when a player moves a piece, revealing an attacking piece behind it that gives check. For example, a white knight is located between the black king and a white rook on the same rank. If the white knight were to move, the black king would then be in check by the white rook. If the knight also gives check to the black king, this would result in a special case of discovered check known as a double check.