What is Discovered Check?

A Discovered Check in chess refers to a check given by a line piece (rook, bishop, or queen) when another piece moves out of its way. Essentially, the said piece discovers the check by moving to a new square, thereby unblocking the line piece's attack on the opposing king. It's a powerful tactic as it potentially allows the player to simultaneously threaten two pieces, the checked king and another piece with the piece moving away.