Check (Chess): definition, rules, and uses
Check
Definition
In chess, check is a condition in which a player’s king is under immediate attack by one or more of the opponent’s pieces. If a king is in check, the rules require the player to make a move that removes the threat on that same turn; no other type of move is legal while the king remains in check.
Rules & Mechanics
- Legal Responses: A player must eliminate the check by
- Moving the king to a safe square,
- Capturing the attacking piece, or
- Interposing another piece between the king and the attacker (if the attack is not delivered by a knight).
- Notation: A single plus sign “
+” is appended to the move that gives check (e.g.,Qh5+). A double plus “++” or the hash “#” is sometimes used for double check or checkmate, though modern algebraic notation prefers “#” exclusively for mate. - Illegality: A player may never make a move that leaves—or places—his or her own king in check. Doing so is an illegal move, and tournament rules prescribe penalties or time adjustments when it happens.
Usage in Play
Checks range from routine nuisance moves to decisive tactical blows. Players exploit checks to force the opponent’s replies, gain tempi, or initiate mating attacks. Because checks must be answered immediately, they are powerful forcing tools in combinations and endgame techniques such as perpetual check.
Tactical & Strategic Significance
- Discovered Check: One piece moves away, unveiling a long-range attack from another piece (e.g., bishop or rook). Discovered checks often win material because the moving piece may simultaneously create a second threat.
- Double Check: Both the moved piece and the unmasked piece give check. Only a king move can escape, making double checks especially potent.
- Smothered Check: A check delivered to a king that is boxed in by its own pieces—famously with a knight on f7 or f2 leading to mate.
- Perpetual Check: A sequence of endless checks that forces a draw; crucial in positions where the attacker is otherwise lost.
- Strategic Use: Sacrifices (e.g., Greek Gift Bxh7+) rely on forcing checks to drag the king into the open. In endgames, checks with the queen or rook from behind (the “rear-check” motif) herd the king toward mating nets or promote pawns.
Historical Notes
The concept of check dates back to the Persian game Shatranj; the term comes from the Persian word “shāh” meaning “king.” Over centuries the exclamation “Shah!” evolved into the English “check,” while “Shah mat” became “checkmate.” Early European rule sets differed on whether announcing “Check!” verbally was obligatory; modern regulations no longer require vocal announcements.
Illustrative Examples
1. Simple Check to Win Material
In the opening line 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Nxe4? 6. d4! Black’s knight is pinned and White threatens d5, but an even cleaner refutation is 6... b5 7. Bb3 d5 8. dxe5 Be6?? 9. Nbd2!? (…) culminating in Re1+, winning back material with interest. The check on the open e-file decides the tactical sequence.
2. Double Check in the “Immortal Game” (Anderssen vs. Kieseritzky, London 1851)
Position after 18. Bf1!!
Black’s king on g8 faces a spectacular combination: 18... Qxa1 19. Qe7+!! (double check from queen and bishop) 19... Nxe7 20. Nf6#. Only king moves are legal in double check, leading directly to mate.
3. Perpetual Check Saves the Game (Kasparov vs. Deep Blue, 1997 Game 3)
Kasparov avoided defeat by forcing a perpetual with queen checks along the dark squares: Qe8+ Qf8 Qe7+ Qf7, repeating the position. Against computer precision, perpetual check remains a vital human resource.
4. Smothered Mate Pattern
Classic finish: 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nd4 4. Nxe5 Qg5 5. Nxf7?? Qxg2 6. Rf1 Qxe4+ 7. Be2 Nf3#.
The final knight move delivers checkmate; the king is smothered by its own pieces. The decisive blow begins with a check that forces a series of inevitabilities.
Interesting Facts & Anecdotes
- Under FIDE rules, if a player’s mobile phone rings while their king is in check, the game is lost—an amusing modern twist on “always answer the check first!”
- The fastest possible check is
1. e4 1... e5 2. Qh5+; however, it is considered dubious because it violates opening principles. - World Champion Emanuel Lasker reportedly advised beginners: “When you see a good move, look for a better one—unless it’s check, then look three times.”
- Double checks are unique: no capture or block can neutralize both sources simultaneously; screens in movies often misuse the idea, showing a blocked double check—something impossible in real play!
Summary
Check is the central tactical motif of chess, embodying the game’s ultimate objective: the safety of the king. Mastery of giving, meeting, and—when necessary—ignoring phantom (illusory) checks differentiates experienced players from novices and fuels many of the game’s most beautiful combinations.