What "discovered attack" means in chess

A discovered attack is a tactical maneuver in which one piece moves to reveal an attack by another piece behind it. The moved piece is usually a less valuable piece, such as a pawn or a knight, and the piece behind it is a more powerful piece, such as a queen or a rook. The attack is often unexpected and can be used to win material or put pressure on the opponent's position. It is one of the most powerful and versatile tactics, and is often used by advanced players to gain an advantage in the game.