Chess is a recreational and competitive game for 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 in the second half of the 15th century after evolving from similar, much older games of Indian origin.
Today, chess is one of the world's most popular games, played by an estimated 605 million people worldwide in clubs, offline, by correspondence (mail and e-mail), in tournaments (amateur and professional) and informally. Aspects of art and science are found in chess composition and theory. Chess is also advocated as a way of enhancing mental prowess.
The game is played on a square chequered chessboard. At the start, each player ("white" and "black") 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. Theoreticians have developed extensive chess strategies and tactics since the game's inception.