Chess is a recreational and competitive game played between two players. Sometimes called Western chess or international chess to distinguish it from its predecessors and other chess variants, the current form of the game emerged in Southern Europe during the second half of the 15th century after evolving from similar, much older games of Indian and Persian origin. Today, chess is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.

The game is played on a square chequered chessboard with 64 squares arranged in an eight-by-eight square. At the start, each player (one controlling the white pieces, the other controlling the black pieces) controls sixteen pieces: one king, one queen, two rooks, two knights, two bishops, and eight pawns. The object of the game is to checkmate the opponent's king, whereby the king is under immediate attack (in "check") and there is no way to remove it from attack on the next move.

The tradition of organized competitive chess started in the sixteenth century and has developed extensively. Chess today is a recognized sport of the International Olympic Committee. The first official World Chess Champion, Wilhelm Steinitz, claimed his title in 1886; Viswanathan Anand is the current World Champion. Theoreticians have developed extensive chess strategies and tactics since the game's inception. Aspects of art are found in chess composition.

One of the goals of early computer scientists was to create a chess-playing machine. Today's chess is deeply influenced by the abilities of current chess programs and the ability to play against others online. In 1997, Deep Blue became the first computer to beat the reigning World Champion in a match when it defeated Garry Kasparov by a score of 3.5-2.5.

Rules

main: Rules of chess For a simple demonstration of the gameplay, see sample chess game.

Setup

Chess is played on a square board of eight rows (called ranks and denoted with numbers 1 to 8) and eight columns (called files and denoted with letters a to h) of squares. The colors of the sixty-four squares alternate and are referred to as "light squares" and "dark squares". The chessboard is placed with a light square at the right hand end of the rank nearest to each player, and the pieces are set out as shown in the diagram, with each queen on its own color.

The pieces are divided, by convention, into white and black sets. The players are referred to as "White" and "Black", and each begins the game with sixteen pieces of the specified color. These consist of one king, one queen, two rooks, two bishops, two knights and eight pawns. White moves first. The players alternate moving one piece at a time (with the exception of castling, when two pieces are moved simultaneously). Pieces are moved to either an unoccupied square, or one occupied by an opponent's piece, capturing it and removing it from play. With one exception (en passant), all pieces capture opponent's pieces by moving to the square that the opponent's piece occupies.