What "absolute pin" means in chess

An absolute pin occurs when a piece is unable to move without exposing a more valuable piece or the king to an attack. In an absolute pin, the pinned piece is immobilized and cannot move because it would result in a loss of material or checkmate.

For example, if a rook is pinned to a king by an opposing bishop, the rook is unable to move as it would expose the king to check. Similarly, if a knight is pinned to a queen by an opposing rook, the knight is unable to move without the queen being captured.

Absolute pins are more powerful than partial pins, where a pinned piece can still move along a line of attack that doesn't expose the more valuable piece or the king. Absolute pins can be an effective tactic, as they can limit the mobility of the pinned piece and make it more vulnerable to capture.