Flight square
In chess, a flight square or escape square is a safe square to which a king or other piece can move if it is threatened. A bishop sometimes begins to get hemmed in after the Morphy Defence is used, and c2–c3 may be used to create an extra escape square.
One way to get a king out of check is to move to a flight square on the next move. The other ways to get out of check are to the checking piece or to a piece to block the check. If the checked king has no flight square and there is no other way to get out of check, it is checkmate.
One way to win from an opponent is to dominate a piece by removing all of its flight squares, then threatening to capture it.
