Chess is a recreational and competitive strategy 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 Asian origin. Today, chess is one of the world's most popular sports, played by an estimated 605 million people worldwide in clubs, online, 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.
The tradition of competitive chess began in the 16th century. The first official World Chess Champion, Wilhelm Steinitz, claimed his title in 1886; his modern equivalent, Vladimir Kramnik, is the 14th Champion in the lineage. There are also biennial world team events called Chess Olympiads. Since the 20th century, two international organizations, the World Chess Federation and the International Correspondence Chess Federation have organized and overseen the top chess competitions and international titles.
One of the goals of early computer scientists was to create a chess-playing machine, and today's chess is deeply influenced by the abilities of current chess programs. In 1997, a match between Garry Kasparov, then World Champion, and IBM's Deep Blue chess program proved for the first time that computers are able to beat even the strongest human players. The popularity of online chess coincided with the growth of the Internet, which started in the mid 1990s. As of 2005, it was estimated that 285 million people play online.
