The king is the most important piece in the game of chess. It may move to any adjoining square; it may also perform, in tandem with the rook, a special move called castling. If a player's king is threatened with capture, it is said to be in check, and the player must remove the threat of capture immediately. If this cannot be done, the king is said to be in checkmate, resulting in a loss for that player. A player cannot make any move that places their own king in check. Despite this, the king can become a strong offensive piece in the endgame or, rarely, the middlegame.
The knight is a piece in the game of chess, represented by a horse's head and neck. It moves two squares vertically and one square horizontally, or two squares horizontally and one square vertically, jumping over other pieces. Each player starts the game with two knights on the b- and g-files, each located between a rook and a bishop.
The pawn is the most numerous and weakest piece in the game of chess. It may move one square directly forward, it may move two squares directly forward on its first move, and it may capture one square diagonally forward. Each player begins a game with eight pawns, one on each square of their second rank. The white pawns start on a2 through h2; the black pawns start on a7 through h7.
In chess, a pin is a tactic 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. The pin is one of the most powerful chess tactics.
Algebraic notation is the standard method for recording and describing the moves in a game of chess. It is based on a system of coordinates to uniquely identify each square on the board. It is now almost universally used by books, magazines, newspapers and software, and is the only form of notation recognized by FIDE, the international chess governing body.
This glossary of chess explains commonly used terms in chess, in alphabetical order. Some of these terms have their own pages, like fork and pin. For a list of unorthodox chess pieces, see Fairy chess piece; for a list of terms specific to chess problems, see Glossary of chess problems; for a list of named opening lines, see List of chess openings; for a list of chess-related games, see List of chess variants; for a list of terms general to board games, see Glossary of board games.
Circe chess is a chess variant in which captured pieces return to their starting positions as soon as they are captured. The game was invented by French composer Pierre Monréal in 1967 and the rules of Circe chess were first detailed by Monréal and Jean-Pierre Boyer in an article in Problème, 1968. It is named for the enchantress Circe, who in the Odyssey instructs Odysseus on how to enter the Underworld and return, just as pieces in Circe chess can return after being killed.
Capablanca chess is a chess variant invented in the 1920s by World Chess Champion José Raúl Capablanca. It incorporates two new pieces and is played on a 10×8 board. Capablanca believed that chess would be played out in a few decades. This threat of "draw death" for chess was his main motivation for creating a more complex version of the game.
A fairy chess piece, variant chess piece, unorthodox chess piece, or heterodox chess piece is a chess piece not used in conventional chess but incorporated into certain chess variants and some unorthodox chess problems, known as fairy chess. Compared to conventional pieces, fairy pieces vary mostly in the way they move, but they may also follow special rules for capturing, promotions, etc. Because of the distributed and uncoordinated nature of unorthodox chess development, the same piece can have different names, and different pieces can have the same name in various contexts.
Forsyth–Edwards Notation (FEN) is a standard notation for describing a particular board position of a chess game. The purpose of FEN is to provide all the necessary information to restart a game from a particular position.
Chess notation systems are used to record either the moves made or the position of the pieces in a game of chess. Chess notation is used in chess literature, and by players keeping a record of an ongoing game. The earliest systems of notation used lengthy narratives to describe each move; these gradually evolved into more compact notation systems. Algebraic notation is now the accepted international standard, with several variants. Descriptive chess notation was used in English- and Spanish-language literature until the late 20th century, but is now obsolescent. Portable Game Notation (PGN) is a text file format based on English algebraic notation which can be processed by most chess software. Other notation systems include ICCF numeric notation, used for international correspondence chess, and systems for transmission using Morse code over telegraph or radio. The standard system for recording chess positions is Forsyth–Edwards Notation (FEN).
In chess, a relative value is a standard value conventionally assigned to each piece. Piece valuations have no role in the rules of chess but are useful as an aid to assessing a position.
ICCF numeric notation is the official chess notation system of the International Correspondence Chess Federation. The system was devised for use in international correspondence chess to avoid the potential confusion of using algebraic notation, as the chess pieces have different abbreviations depending on language.
In chess, promotion is the replacement of a pawn with a new piece when the pawn is moved to its last rank. The player replaces the pawn immediately with a queen, rook, bishop, or knight of the same color. The new piece does not have to be a previously captured piece. Promotion is mandatory when moving to the last rank; the pawn cannot remain as a pawn.
Judkins shogi is a modern variant of shogi, however it is not Japanese. Credit for its invention has been given to Paul Judkins of Norwich, UK, prior to April 1998.
Omega Chess is a commercial chess variant designed and released in 1992 by Daniel MacDonald. The game is played on a 10×10 board with four extra squares, each added diagonally adjacent to the corner squares. The game is laid out like standard chess with the addition of a champion in each corner of the 10×10 board and a wizard in each new added corner square.
Okisaki shogi is a modern variant of shogi. It was developed by Masayuki Nakayachi c. 1996 from suggestions by German chess player Ralph Blockhaus.
Wildebeest chess is a chess variant created by R. Wayne Schmittberger in 1987. The Wildebeest board is 11×10 squares. Besides the standard chess pieces, each side has two camels and one "wildebeest" - a piece which may move as either a camel or a knight.
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.
Dynamo chess is a chess variant invented by chess problemists Hans Klüver and Peter Kahl in 1968. The invention was inspired by the closely related variant push chess, invented by Fred Galvin in 1967. The pieces, board, and starting position of Dynamo chess are the same as in orthodox chess, but captures are eliminated and enemy pieces are instead "pushed" or "pulled" off the board. On any given move, a player can make a standard move as in orthodox chess, or execute a "push move" or a "pull move". A move that is either a push move or a pull move is called a "dynamo move".
