Checks - Chess Definition and Types

Checks

Definition

A check is a move that directly attacks the opponent’s king. The side in check must immediately make a legal move that ends the check. In notation, a checking move is typically marked with a plus sign “+”; checkmate is marked with “#” (or “++” in older texts).

Usage

Checks are forcing moves: they limit the opponent’s replies to a small set of legal defenses. Because they force concrete responses, checks are central to calculation. Players often begin analysis with “checks, captures, and threats” to find forcing lines, tactical shots, and mating nets. Checks can gain tempo, drive the king into the open, deflect pieces, or force perpetual check to draw.

Rules and Notation

• You cannot make a move that leaves your own king in check.
• If your king is in check, you must respond immediately by:
  1. Moving the king to a safe square, or
  2. Capturing the checking piece, or
  3. Interposing a piece to block the line of attack (if the check is by a rook, bishop, or queen).
• A cross-check is a special interposition that also gives check back to the opponent.
• Notation: “+” means check; “#” means checkmate. Historically, “++” sometimes indicated mate or double check, but modern PGN uses “#” for mate and no special symbol for double check.

Types of Checks

Direct check

A single piece immediately attacks the king. Example: in the Sicilian, 1. e4 c5 2. Nf3 d6 3. Bb5+ gives a developing check that can steer the game into favorable structures.

Discovered check

One piece moves, revealing a line from a long-range piece (bishop, rook, or queen) to the king. This can be devastating because the moving piece may also create an additional threat. Example motif: White rook on e1 and bishop on c4; moving the bishop with 1. Bxf7+ uncovers pressure on the e-file while checking.

Double check

A special case of discovered check where both the piece that moves and the previously blocked piece give check simultaneously (for example, a knight moves to uncover a bishop’s line while the knight itself also gives check). The only legal reply to a double check is a king move—blocking or capturing one checker doesn’t stop the other.

Quiet (or soft) check

A non-sacrificial check that doesn’t capture or look flashy, but improves coordination or drives the king onto a worse square. These often appear in endgames to win tempi or force favorable king placement.

Checking sacrifice

Sacrificing material to deliver check, often to rip open the king’s shelter or force it into a mating net. Classic example: the “Greek Gift” 1. Bxh7+! Kxh7 2. Ng5+ followed by Qh5+ drives the king into the open.

Cross-check

Interposing a piece to block a check while simultaneously giving check back (e.g., …Bd4+ against a rook’s file check). Cross-checks can force exchanges that defuse an attack.

Perpetual check

A sequence where the attacker can check forever, because any deviation would lose the initiative or material. This typically yields a draw by threefold repetition (or by agreement). See also perpetual check.

Defending Against Checks

The three standard defenses

• King flight: move the king to a safe square.
• Capture: remove the checking piece (ensure the capturing piece isn’t pinned or overloaded).
• Interpose: block with a piece (only against sliding-piece checks).

Look for cross-checks to gain the initiative. Beware of tactical resources like discovered checks after your interposition—e.g., blocking a bishop’s check on a diagonal where your king can be skewered next move.

Strategic and Historical Notes

Strategic significance

• Checks gain tempo: every check forces a reply, which can help you bring more pieces into the attack or force a favorable endgame (e.g., checking to win a tempo and capture an unprotected piece).
• Mating nets: series of checks can herd the king onto a mating pattern like smothered mate or Anastasia’s mate.
• Resource for the defender: perpetual check is a key drawing mechanism even in lost positions.
• Calculation heuristic: when calculating, first scan for forcing checks; many tactical shots are only possible because of a precise checking move.

Historical anecdotes

• In older chess traditions, announcing “check” aloud was common and at times required. Modern FIDE rules do not require verbal announcement.
• The word “check” derives from the Persian “shah” (king); “checkmate” comes from “shah mat” (“the king is helpless”).
• Famous attacking games often feature a cascade of checks. For example, Morphy’s “Opera Game” ends with a crisp checking sequence to mate. See example below.
• The “windmill” (or see-saw) is a celebrated repeated discovered-check motif, notably in games such as Torre vs. Lasker, Moscow 1925, where a rook and bishop deliver alternating checks to win massive material. See also windmill.

Examples

1) Forcing checks to mate: Morphy’s Opera Game (Morphy vs. Duke Karl/Count Isouard, Paris 1858)

Morphy uses a series of forcing moves and checks to finish. Final phase shown here:

2) Perpetual check to draw

Typical pattern: the attacker’s queen checks along dark squares around an exposed king with no safe hideout, for instance: …Kg8 with pawns on f7–g7–h7 and a weakened light-square complex; White’s queen oscillates Qe8+ and Qg6+, and any attempt to interpose drops material or allows mate. After three repetitions of the same position, the game is drawn by the threefold repetition rule.

3) Double check motif

Common pattern: a knight jumps with check while uncovering a bishop’s diagonal—Nf6++ from d5 or g4, for example, where both the knight and bishop check the king. Because only a king move can answer a double check, such moves often lead to forced mates or decisive material gains. See discovered attack for related ideas.

4) Zwischenzug (in-between) check

Instead of recapturing immediately, a player throws in a check to gain time or improve the outcome. Example pattern: 1. Rxd5? Qc1+! 2. Rd1 Qxd1+ with a favorable simplification for Black. See also zwischenzug.

Practical Tips

• When attacking: list all checks first. If any check leads to a forced win, you don’t need to calculate lesser options.
• When defending: prioritize king safety and look for counter-checks or cross-checks to seize the initiative.
• Endgames: “quiet checks” can win tempi to shoulder the enemy king or force a pawn promotion race in your favor.
• Avoid pointless checks that improve the opponent’s king activity, especially in endgames.