The game's present form emerged in Europe during the second half of the 15th century, an evolution of an older Indian game, Shatranj. Theoreticians have developed extensive chess strategies and tactics since the game's inception. Computers have been used for many years to create chess-playing machines, and their abilities and insights have contributed significantly to modern chess theory. One, Deep Blue, was the first machine to beat a reigning World Chess Champion when it defeated Garry Kasparov in 1997.

The tradition of organized competitive chess started during the 16th century. The first official World Chess Champion, Wilhelm Steinitz, claimed his title in 1886; the current World Champion is Viswanathan Anand from India. In addition to the World Championship, there is also the Women's World Championship, the Junior World Championship, the World Senior Championship, the Correspondence Chess World Championship, the World Computer Chess Championship, and Blitz and Rapid World Championships (see fast chess). The Chess Olympiad is a popular competition among teams from different nations. Online chess has opened amateur and professional competition to a wide and varied group of players.

Chess is a recognized sport of the International Olympic Committee, and is led by the FIDE. 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. Some other popular forms of chess are fast chess and computer chess, and there are many chess variants.

The official rules of chess are maintained by the World Chess Federation. Along with information on official chess tournaments, the rules are described in the FIDE Handbook, section Laws of Chess. For a demonstration of the gameplay, see a sample chess game.

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 always moves first. After the initial move, the players alternately move one piece at a time (with the exception of castling, when two pieces are moved). Pieces are moved to either an unoccupied square, or one occupied by an opponent's piece, capturing it and removing it from play. With the sole exception of en passant, all pieces capture opponent's pieces by moving to the square that the opponent's piece occupies.

Each chess piece has its own style of moving.

A player may not make any move which allows the king to be captured. If such a move is not possible the game ends with a checkmate, if king is under immediate attack or stalemate, if it is not.

In the diagrams, the dots mark the squares where the piece can move if no other pieces (including one's own piece) are on the Xs between the piece's initial position and its destination.