It began as a model of an army
Chess grew out of a game called chaturanga, played in India by around the sixth century AD. Its name meant four divisions, the four parts of an Indian army: infantry, cavalry, elephants and chariots. They became the PAWN, the KNIGHT, the piece that later turned into the BISHOP, and the ROOK — whose name comes from rukh, the Persian word for chariot, and has nothing to do with the bird.
The game passed to Persia, where it was called shatranj, then spread with the Islamic world into Spain and on across Europe. CHECKMATE comes from the Persian shah mat, usually translated as the king is helpless, or the king is defeated. The KING is never actually taken.
The queen used to be the weakest piece
In the older game, the piece next to the king was a counsellor or vizier, and it could move just one SQUARE diagonally — one of the feeblest pieces on the BOARD. Games were slow and could take hours to reach a result.
Around 1475, probably in Spain, players began letting that piece move any distance in any straight line, and in Europe it became the QUEEN. The new game was nicknamed the chess of the mad queen, and it changed everything: attacks became fast and dangerous, and most of modern chess STRATEGY dates from this change. The bishop gained its long diagonal move at around the same time.
Special moves and odd rules
Castling is the one MOVE in which two pieces move at once: the king steps two squares towards a rook, and the rook jumps over to the other side of it. It is allowed only if neither has moved, and the king may not castle out of, through or into check. A pawn that reaches the far side of the board is promoted, almost always to a queen, so a player can in theory have nine queens.
STALEMATE, when the player to move has no legal move but is not in check, counts as a draw. A GAMBIT, from an Italian word for tripping someone up, is an OPENING in which a player offers a pawn to gain quicker development. A SACRIFICE gives up material deliberately, trusting the TACTICS that follow to win it back with interest. To CAPTURE is simply to take a piece, and every good player learns to DEFEND first.
Ratings and young grandmasters
Players are ranked by the Elo system, devised by the Hungarian-American physics professor Arpad Elo. Beating a stronger PLAYER gains more points than beating a weaker one, and the numbers are recalculated after every rated game. The highest rating ever reached, 2882, belongs to Magnus Carlsen.
The youngest grandmaster so far is Abhimanyu Mishra of the United States, who earned the title in 2021 at twelve years and four months. Rapid improvement by very young players is now common, partly because computer programs let anyone practise against strong opposition. The ENDGAME, with few pieces left, is where many TOURNAMENT games are decided, and some endings are now completely solved. Our artificial intelligence page covers the machines that changed how the game is studied.