A pin is one of the most powerful tactics in chess in which a defending piece cannot move out of an attacking piece's line of attack without exposing a more valuable defending piece. Moving the attacking piece to effect the pin is called pinning; the defending piece restricted by the pin is described as pinned. Only a piece that can move any number of squares along a horizontal, vertical, or diagonal line can pin. Any piece can be pinned except the king.
Alice chess is a chess variant invented in 1953 by V. R. Parton which employs two chessboards rather than one, and a slight alteration to the standard rules of chess. The game is named after the main character "Alice" in Lewis Carroll's work Through the Looking-Glass, where transport through the mirror into an alternative world is portrayed on the chessboards by the after-move transfer of chess pieces between boards A and B.
A Grimshaw is a device found in chess problems in which two pieces arriving on a particular square mutually interfere with each other. It is named after the 19th-century problem composer Walter Grimshaw. The Grimshaw is one of the most common devices found in directmates.
The Novotny is a device found in chess problems named after a problem from 1854 by Antonín Novotný, though the first example was composed by Henry Turton in 1851. A piece is sacrificed on a square where it could be taken by two different opposing pieces, but whichever makes the capture, it interferes with the other. It is essentially a Grimshaw brought about by a sacrifice on the critical square.
The Plachutta is a device found in chess problems wherein a piece is sacrificially positioned in blockade to deny coverage of multiple distant squares required by the opposition. For example, two of an opponent's bishops, queen, or rooks are defending locations through an intersection square, and an enemy unit moved into that square blocks disrupts coverage in such a way that, even if captured, the previous defensive situation cannot be restored.
Madrasi chess is a chess variant invented in 1979 by Abdul Jabbar Karwatkar. The game uses the conventional rules of chess with the addition that when a piece is attacked by a piece of the same type but opposite colour it is paralysed and becomes unable to move, capture or give check.
The Opera Game was an 1858 chess game, played at an opera house in Paris. The American master Paul Morphy played against two strong amateurs: the German noble Karl II, Duke of Brunswick, and the French aristocrat Comte Isouard de Vauvenargues. It was played as a consultation game, with Duke Karl and Count Isouard jointly deciding each move for the black pieces, while Morphy controlled the white pieces by himself. The game was played in a box while an opera was performed on stage. Morphy quickly checkmated his opponents following rapid development of material, involving a queen sacrifice.
In chess, a back-rank checkmate is a checkmate delivered by a rook or queen along the opponent's back rank in which the mated king is unable to move up the board because the king is blocked by friendly pieces on the second rank.
Siegbert Tarrasch was a German chess player, considered to have been among the strongest players and most influential theoreticians of the late 19th and early 20th century.
The zwischenzug is a chess tactic in which a player, instead of playing the expected move, first interposes another move posing an immediate threat that the opponent must answer, and only then plays the expected move. It is a move that has a high degree of "initiative". Ideally, the zwischenzug changes the situation to the player's advantage, such as by gaining material or avoiding what would otherwise be a strong continuation for the opponent.
In chess, an X-ray or X-ray attack is a tactic where a piece indirectly controls a square from the other side of an intervening piece. Generally, a piece performing an X-ray either:
In chess, a tactic is a sequence of moves that each makes one or more immediate threats – a check, a material threat, a checkmating sequence threat, or the threat of another tactic – that culminates in the opponent's being unable to respond to all of the threats without making some kind of concession. Most often, the immediate benefit takes the form of a material advantage or mating attack; however, some tactics are used for defensive purposes and can salvage material that would otherwise be lost, or to induce stalemate in an otherwise lost position.
In chess and similar games, check is a condition that occurs when a player's king is under threat of capture on the opponent's next turn. A king so threatened is said to be in check. A player must get out of check if possible by moving the king to an unattacked square, interposing a piece between the threatening piece and the king, or capturing the threatening piece. If the player cannot remove the check by any of these options, the game ends in checkmate and the player loses. Players cannot make any move that puts their own king in check.
In chess, a pure mate is a checkmate position such that the mated king is attacked exactly once, and prevented from moving to any of the adjacent squares in its field for exactly one reason per square. Each of the squares in the mated king's field is attacked or "guarded" by one—and only one—attacking unit, or else a square which is not attacked is occupied by a friendly unit, a unit of the same color as the mated king. Some authors allow that special situations involving double check or pins may also be considered as pure mate.
In chess, the exchange is a material imbalance of a minor piece for a rook. The side which wins the rook is said to have won the exchange, while the other player has lost the exchange, since the rook is usually more valuable. Alternatively, the side having a rook for a minor piece is said to be up the exchange, and the other player is down the exchange. The opposing captures often happen on consecutive moves, although this is not strictly necessary. It is generally detrimental to lose the exchange, although occasionally one may find reason to purposely do so; the result is an exchange sacrifice. The minor exchange is an uncommon term for the exchange of a bishop and knight.
In chess, a decoy is a tactic that lures an enemy man off its square and away from its defensive role. Typically this means away from a square on which it defends another piece or threat. The tactic is also called a deflection. Usually the piece is decoyed to a particular square via the sacrifice of a piece on that square. A piece so sacrificed is called a decoy. When the piece decoyed or deflected is the king, the tactic is known as attraction. In general in the middlegame, the sacrifice of a decoy piece is called a diversionary sacrifice.
The fourth World Chess Championship was held in Havana from 1 January to 28 February 1892. Defending champion William Steinitz narrowly defeated challenger Mikhail Chigorin.
The following outline is provided as an overview of and topical guide to chess:
Hostage chess is a chess variant invented by John A. Leslie in 1997. Captured pieces are not eliminated from the game but can reenter active play through drops, similar to shogi. Unlike shogi, the piece a player may drop is one of their own pieces previously captured by the opponent. In exchange, the player returns a previously captured enemy piece which the opponent may drop on a future turn. This is the characteristic feature of the game.
Trapping the queen is a tactical motif which occurs in both amateur and master games. The tactic is similar to a mating net, whose target is the defender's king, rather than his queen. When the opponent's queen is successfully trapped, it usually results in his immediate resignation.
