the term check-rook was used for a move that checked the king and attacked a rook at the same time . Until the early 20th century a player was expected to announce "check" when making a checking move, and some sources of rules even allowed a player to ignore an unannounced check . Modern practice In informal games, most players still announce "check"; however, this is no longer required under the rules of chess and is not encouraged in formal games . In the FIDE rules for rapid chess, if a player leaves or places their king in check or commits any other illegal move, their opponent can claim a win. In algebraic chess notation, a "+" is normally written after a checking move. A minority of publications, most notably ECO, omit any mention of check. Checking in tactics and strategy Sometimes checking an opponent provides no benefit to the checking player. This is called a "useless check" and it may even provide the checked opponent with a tempo (move opportunity) to move the king into a safer position . For example, 1.e4 e6 2.d4 Bb4+ does nothing for Black and in fact causes him to lose a tempo after 3.c3 A check given with the sole intention of delaying an inevitable defeat by one move is referred to as a "spite check", and may be considered somewhat unsporting . There are many instances, however, when checking the opponent's king may be a useful tactic or part of a tactic, either in attacking or in defense. Checking is often used in combinations with many other tactics or simply to an opponent into a position where their king can be checkmated, otherwise taken advantage of, or is otherwise worse for the opponent. Some attacks involve numerous checks to force an opponent into a losing position, especially when the king is exposed. Some uses of checking: Repetitive checking to prevent losing the game (draw by perpetual check) Royal fork (fork of the king and queen) or other forks involving the king Forcing an exchange Preventing castling by forcing the king to move Opening a line of attack by another piece (discovered attack) Limiting the opponent's response to a move by moving with a discovered check Forcing the king to clear the way to capturing another piece (absolute skewer) Pushing a defending piece into an absolute pin Deflecting the king from protecting a