Check (chess)

A check is a condition in chess, shogi, xiangqi, and janggi that occurs when a player's king (or general in xiangqi and janggi) is under threat of on their opponent's next turn. A king so threatened is said to be "in check". A player must get out of check, if possible, by interposing a piece between the threatening piece and the king, capturing the threatening piece, or moving the king to a square where it is no longer in check. If the player cannot move out of check, the game ends in checkmate and the player loses. Players cannot make any move that puts their own king in check.
Introduction.
A check is the result of a move that places the opposing king under an immediate threat of capture by at least one of the player's pieces. Making a move that checks is sometimes called "giving check". If the king is in check and the checked player has no legal move to get out of check, the king is checkmated and the player loses.
Under the standard rules of chess, a player may not make any move that places or leaves their king in check. A player may move the king, capture the threatening piece, or block the check with another piece. A king cannot itself directly check the opposing king, since this would place the first king in check as well. A move of the king could expose the opposing king to a discovered check by another piece, however.
In informal games, it is common to announce "check" when making a move that puts the opponent's king in check. In formal competition, however, announcing check is discouraged.
In fast chess, depending on the rules in effect, placing or leaving one's king in check may result in immediate loss of the game.
Getting out of check.
There may be up to three possible ways to get a king out of a single check on the following move:
In the position in the first diagram, White can get out of check by any of three methods:
If a king is placed in double check, the king must get out of both checks on the following move. Since it is impossible to capture both checking pieces or block both lines of attack in a single move, a double check can be escaped only by moving the king out of check. The king itself, however, can capture one of the checking pieces or another enemy piece if it brings the king into safety. If none of these possibilities can get the king out of check, then it is checkmated and the game is lost by the checkmated player.
Types of checks.
A simple and very common type of check is when a piece moves to directly attack the opposing king only by itself. Sometimes such a check is part of a chess tactic such as a fork, a skewer, or a discovered attack on another piece. In some cases, a check can be used to defend against such tactics.
There are also a few more special types of check:
Announcing check and notation.
Until the early 20th century a player was expected to announce "check" when making a checking move, and some sources of rules even required it . In friendly games most players still announce "check". However announcing "check" is not required under the rules of chess and it is usually not done in formal games .
In algebraic chess notation, a checking move is recorded like any other move, except that a "+" is normally written after the move.
In the FIDE rules for rapid chess, if a player leaves their king in check or commits any other illegal move their opponent can claim a win.
Historical.
Less commonly (and obsolete), the warning "garde" can be said when a player directly attacks the opponent's queen in a similar way. This was mostly abandoned in the 19th century . The same move can be both "check" and "garde" simultaneously. Before the queen acquired its current move (about 1495) the rook was the most powerful piece. At that time the term "check-rook" was used for a move that checked the king and attacked a rook at the same time .
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 force an opponent into a position where the opposing 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. An unexpected check in a forced combination or an overlooked cross-check in a planned series of checks may serve as sort of a zwischenzug, foiling the plan.
Some uses of checking:
History.
The idea of warning that the king was under attack (announcing "check" in modern terminology) is present in the earliest descriptions of chess rules, in Persian/Arabian manuscripts. This was done to avoid the early and accidental end of a game. Later the Persians added the additional rule that a king could not be moved into check or left in check. As a result, the king could not be captured .
In this usage, the words "check" and "chess" come via Arabic from Persian "shāh", meaning "king" or "monarch" .
References.
Bibliography