In the game of chess, perpetual check is a situation in which one player can play an unending series of checks, from which the defending player cannot escape. This typically arises when the player who is checking feels their position in the game is inferior, they cannot deliver checkmate, and wish to force a draw.
A draw by perpetual check is no longer one of the rules of chess, but will eventually allow a draw claim by either threefold repetition or the fifty-move rule. Players usually agree to a draw long before that.[1]
Perpetual check can also occur in other forms of chess, although the rules relating to it might be different. For example, giving perpetual check is not allowed in shogi and xiangqi, where doing so leads to an automatic loss for the giver.