Chess is a board game for two players. It is sometimes called international chess or Western chess to distinguish it from related games such as xiangqi and shogi.
Chess strategy is the aspect of chess play concerned with evaluation of chess positions and setting goals and long-term plans for future play. While evaluating a position strategically, a player must take into account such factors as the relative value of the pieces on the board, pawn structure, king safety, position of pieces, and control of key squares and groups of squares. Chess strategy is distinguished from chess tactics, which is the aspect of play concerned with the move-by-move setting up of threats and defenses. Some authors distinguish static strategic imbalances, which tend to persist for many moves, from dynamic imbalances, which are temporary. This distinction affects the immediacy with which a sought-after plan should take effect. Until players reach the skill level of "master", chess tactics tend to ultimately decide the outcomes of games more often than strategy. Many chess coaches thus emphasize the study of tactics as the most efficient way to improve one's results in serious chess play.
The king is the most important piece in the game of chess; the object of the game is to capture the king by checkmate, and the loss of the king entails loss of the game. 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 queen is the most powerful piece in the game of chess. It can move any number of squares vertically, horizontally or diagonally, combining the powers of the rook and bishop. Each player starts the game with one queen, placed in the middle of the first rank next to the king. Because the queen is the strongest piece, a pawn is promoted to a queen in the vast majority of cases.
The rook is a piece in the game of chess. It may move any number of squares horizontally or vertically without jumping, and it may capture an enemy piece on its path; it may participate in castling. Each player starts the game with two rooks, one in each corner on their side of the board.
The bishop is a piece in the game of chess. It moves and captures along diagonals without jumping over intervening pieces. Each player begins the game with two bishops. The starting squares are c1 and f1 for White's bishops, and c8 and f8 for Black's bishops.
A chess piece, or chessman, is a game piece that is placed on a chessboard to play the game of chess. It can be either white or black, and it can be one of six types: king, queen, rook, bishop, knight, or pawn.
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.
The rules of chess govern the play of the game of chess. Chess is a two-player abstract strategy board game. Each player controls sixteen pieces of six types on a chessboard. Each type of piece moves in a distinct way. The object of the game is to checkmate the opponent's king; checkmate occurs when a king is threatened with capture and has no escape. A game can end in various ways besides checkmate: a player can resign, and there are several ways a game can end in a draw.
The endgame is the final stage of a chess game which occurs after the middlegame. It begins when few pieces are left on the board.
Zugzwang is a situation found in chess and other turn-based games wherein one player is put at a disadvantage because of their obligation to make a move; a player is said to be "in zugzwang" when any legal move will worsen their position.
Checkmate is any game position in chess and other chess-like games in which a player's king is in check and there is no possible escape. Checkmating the opponent wins the game.
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 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.
In chess, the exchange is the material difference of a rook for a minor piece. Having a rook for a minor piece is generally advantageous, since the rook is usually more valuable. A player who has a rook for a minor piece is said to be up the exchange, and the other player is down the exchange. A player who wins a rook for a minor piece is said to have won the exchange, while the other player has lost the exchange. The opposing captures often happen on consecutive moves, but this is not strictly necessary. Although it is generally detrimental to lose the exchange, one may occasionally find reason to purposely do so; the result is an exchange sacrifice.
A pawnless chess endgame is a chess endgame in which only a few pieces remain, and no pawns. The basic checkmates are types of pawnless endgames. Endgames without pawns do not occur very often in practice except for the basic checkmates of king and queen versus king, king and rook versus king, and queen versus rook. Other cases that occur occasionally are (1) a rook and minor piece versus a rook and (2) a rook versus a minor piece, especially if the minor piece is a bishop.
In chess, an exchange or trade of chess pieces is a series of closely related moves, typically sequential, in which the two players capture each other's pieces. Any type of pieces except the kings may possibly be exchanged, i.e. captured in an exchange, although a king can capture an opponent's piece. Either the player of the white or the black pieces may make the first capture of the other player's piece in an exchange, followed by the other player capturing a piece of the first player, often referred to as a recapture. Commonly, the word "exchange" is used when the pieces exchanged are of the same type or of about equal value, which is an even exchange. According to chess tactics, a bishop and a knight are usually of about equal value. If the values of the pieces exchanged are not equal, then the player who captures the higher-valued piece can be said to be up the exchange or wins the exchange, while the opponent who captures the lower-valued piece is down the exchange or loses the exchange. Exchanges occur very frequently in chess, in almost every game and usually multiple times per game. Exchanges are often related to the tactics or strategy in a chess game, but often simply occur over the course of a game.
The game of chess is commonly divided into three phases: the opening, middlegame, and endgame. There is a large body of theory regarding how the game should be played in each of these phases, especially the opening and endgame. Those who write about chess theory, who are often also eminent players, are referred to as "chess theorists" or "chess theoreticians".
In chess, checkmate pattern is a recognizable/particular/studied arrangements of pieces that delivers checkmate. Several checkmate patterns occur frequently enough to have acquired specific names in chess commentary. The diagrams that follow show these checkmates with White checkmating Black.
The following outline is provided as an overview of and topical guide to chess: