Chess


Chess is a board game for two players, played on a square board consisting of 64 squares arranged in an 8×8 grid. The players, referred to as "White" and "Black", each control sixteen pieces: one king, one queen, two rooks, two bishops, two knights, and eight pawns, with each piece type having a different pattern of movement. An enemy piece may be captured by moving one's own piece onto the square it occupies. The object of the game is to "checkmate" the enemy king. There are also several ways a game can end in a draw.
The recorded history of chess dates back to the emergence of chaturanga in 7th-century India. Chaturanga is also thought to be an ancestor of similar games like,, and. After its introduction to Persia, it spread to the Arab world and then to Europe. The modern rules of chess emerged in Europe at the end of the 15th century, becoming standardized and gaining universal acceptance by the end of the 19th century. Today, chess is one of the world's most popular games, with millions of players worldwide.
Organized chess arose in the 19th century. International chess competitions today are governed by the International Chess Federation FIDE. The first universally recognized World Chess Champion, Wilhelm Steinitz, claimed his title in 1886; Gukesh Dommaraju is the current World Champion, having won the title in 2024.
A large body of chess theory has developed since the game's inception. Aspects of art are found in chess composition, and chess has in turn influenced Western culture and the arts, and has relevance to other fields such as mathematics, computer science, and psychology. One of the goals of early computer scientists was to create a chess-playing machine. In 1997, Deep Blue became the first computer to win a match with a reigning World Champion when it defeated Garry Kasparov. The chess engines of today are significantly stronger than the best human players and have greatly influenced the development of chess theory. Chess, however, is not a solved game.

Rules

The rules of chess are published by FIDE, world governing body of chess, in its Handbook. Rules published by national governing bodies, or by unaffiliated chess organizations, commercial publishers, etc., may differ in some details. FIDE's rules were most recently revised in 2023.

Setup

s come in a wide variety of styles. The Staunton pattern is the most common, and is usually required for competition. Chess sets come with pieces in two colors, referred to as white and black, regardless of their actual color; the players controlling the color sets are referred to as White and Black, respectively. Each set comes with at least the following 16 pieces in both colors: one king, one queen, two rooks, two bishops, two knights, and eight pawns.
The game is played on a square board of eight rows and eight columns. Although it does not affect gameplay, by convention the 64 squares alternate in color and are referred to as and squares.
To start the game, White's pieces are placed on the first rank in the following order, from left to right: rook, knight, bishop, queen, king, bishop, knight, rook. Pawns are placed on each square of the second rank. Black's position mirrors White's, with equivalent pieces on every file. The board is oriented so that the right-hand corner nearest each player is a light square; as a result the white queen always starts on a light square, while the black queen starts on a dark square. This may be remembered by the phrases "white on the right" and "queen on her color".
In competitions, the piece colors are allocated to players by the organizers. In informal games, colors may be decided either by mutual agreement, or randomly, for example by a coin toss, or by one player concealing a white pawn in one hand and a black pawn in the other and having the opponent choose.

Movement

White moves first, after which players alternate turns. One piece is moved per turn. In the diagrams, dots mark the squares to which each type of piece can move if unoccupied by friendly pieces and there are no intervening piece of either color. With the sole exception of en passant, a piece captures an enemy piece by moving to the square it occupies, removing it from play and taking its place. The pawn is the only piece that does not capture the way it moves, and it is the only piece that moves and captures in only one direction. A piece is said to control empty squares on which it could capture, attack squares with enemy pieces it could capture, and defend squares with pieces of the same color on which it could recapture. Moving is compulsory; a player may not skip a turn, even when having to move is detrimental.
  • The king moves one square in any direction. There is also a special move called [|castling] which moves the king and a rook. The king is the most valuable piece—it is illegal to play any move that puts one's king under attack by an opponent piece. A move that attacks the king must be parried immediately; if this cannot be done, the game is lost.
  • A rook can move any number of squares along a rank or file. A rook is involved in the king's castling move.
  • A bishop can move any number of squares diagonally.
  • A queen combines the power of a rook and bishop and can move any number of squares along a rank, file, or diagonal.
  • A knight moves to any of the closest squares that are not on the same rank, file, or diagonal. The knight is the only piece that can leap over other pieces.
  • A pawn can move forward to the unoccupied square immediately in front of it on the same file, or on its first move it can optionally advance two squares along the same file, provided both squares are unoccupied. A pawn can capture an opponent's piece on a square diagonally in front of it by moving to that square. It capture a piece while advancing along the same file, nor can it move to either square diagonally in front without capturing. Pawns have two special moves: the en passant capture and [|promotion].

    Check and checkmate

When a king is under immediate attack, it is in check. A move in response to a check is legal only if it results in a position in which the king is no longer in check. There are three ways to counter a check:
  • Capture the checking piece.
  • Interpose a piece between the checking piece and the king.
  • Move the king to a square where it is not under attack.
The object of the game is to checkmate the opponent; this occurs when the opponent's king is in check, and there is no legal way to get it out of check. In casual games, it is common to announce "check" when putting the opponent's king in check, but this is not required by the rules of chess and is usually not done in tournaments.

Castling

Kings can castle once per game. Castling consists of moving the king two squares toward either rook of the same color, and then placing the rook on the square that the king crossed.
Castling is possible only if the following conditions are met:
  • Neither the king nor the rook has previously moved during the game.
  • There are no pieces between the king and the rook.
  • The king is not in check and does not pass through or finish on a square controlled by an enemy piece.
Castling is still permitted if the rook is under attack, or if the rook crosses an attacked square. It is also still permitted if the king had been in check earlier in the game, provided that the check was resolved without moving the king.

Special pawn moves

Pawns have two special moves:
  • En passant: when a pawn makes a two-square advance to the same rank as an opponent's pawn on an adjacent file, that pawn can capture it en passant, moving to one square behind the captured pawn. A pawn can only be captured en passant on the turn after it makes a two-square advance. In the animated diagram, the black pawn advances two squares from g7 to g5, and the white pawn on f5 takes it en passant, landing on g6.
  • Promotion: when a pawn advances to its, it is promoted and replaced with the player's choice of a queen, rook, bishop, or knight. Usually, pawns are promoted to queens; choosing another piece is called underpromotion. In the animated diagram, the c7-pawn is advanced to c8 and promoted to a queen. If the required piece is not available, an inverted rook is sometimes used as a substitute, but this is not recognized in FIDE-sanctioned games.

    End of the game

Win

A game can be won in the following ways:
  • Checkmate: The opposing king is in check and no move can get it out of check.
  • Resignation: A player may resign, conceding the game to the opponent. If, however, the opponent has no way of checkmating the resigned player, this is a draw under FIDE Laws. Most tournament players consider it good etiquette to resign in a hopeless position.
  • Win on time: In games with a time control, a player wins if the opponent runs out of time, even if the opponent has a superior position, as long as the player has a theoretical possibility to checkmate the opponent were the game to continue.
  • Forfeit: A player who cheats, violates the rules, or violates the rules of conduct specified for the particular tournament can be forfeited. Occasionally, both players are forfeited.

    Draw

There are several ways a game can end in a draw:
  • Stalemate: If the player to move has no legal move, but is not in check, the position is a stalemate, and the game is drawn.
  • Dead position: If neither player is able to checkmate the other by any legal sequence of moves, the game is drawn. For example, if only the kings are on the board, all other pieces having been captured, checkmate is impossible and the game is drawn by this rule. On the other hand, if each player still has a knight, there is a theoretical albeit highly unlikely possibility of checkmate, so this rule does not apply. The dead position rule supersedes an older rule that referred to "insufficient material", thereby extending it to include other positions in which checkmate is impossible, such as blocked pawn endings in which the pawns cannot be attacked.
  • Draw by agreement: In tournament chess, draws are most commonly reached by mutual agreement between the players. The correct procedure is to make a move, to verbally offer the draw, and then to start the opponent's clock. If a draw is offered before making a move, the opponent has the right to ask the player to make a move before making their decision on whether or not to accept the draw offer. Traditionally, players were allowed to agree to a draw at any point in the game, occasionally even without having played a single move. Since the 2000s, efforts have been made to discourage early draws, for example by forbidding draw offers before a certain number of moves have been completed or even forbidding draw offers altogether.
  • Threefold repetition: This most commonly occurs when neither side is able to avoid repeating moves without incurring a disadvantage. The three occurrences of the position need not occur on consecutive moves for a claim to be valid. The addition of the fivefold repetition rule in 2014 requires the arbiter to intervene immediately and declare the game a draw after five occurrences of the same position, consecutive or otherwise, without requiring a claim by either player. FIDE rules make no mention of perpetual check; this is merely a specific type of draw by threefold repetition.
  • Fifty-move rule: If during the previous 50 moves no pawn has been moved and no capture has been made, either player can claim a draw. The addition of the seventy-five-move rule in 2014 requires the arbiter to intervene and immediately declare the game drawn after 75 moves without a pawn move or capture, without requiring a claim by either player. There are several known endgames in which it is possible to force a mate but it requires more than 50 moves before a pawn move or capture is made; examples include some endgames with two knights against a pawn and some pawnless endgames such as queen against two bishops. Historically, FIDE has sometimes revised the fifty-move rule to make exceptions for these endgames, but these exceptions have since been repealed. Some correspondence chess organizations do not enforce the fifty-move rule.
  • Draw on time: In games with a time control, the game is drawn if a player is out of time but no sequence of legal moves would allow the opponent to checkmate the player.
  • Draw by resignation: Under FIDE Laws, a game is drawn if a player resigns but no sequence of legal moves would allow the opponent to checkmate that player.