A game with a few simple rules can still be enormous; the Shannon number, about 10^120, is a rough estimate of how many move sequences are possible in chess, and it comes from Claude Shannon's 1950 work; the number assumes about 30 legal moves in a typical position, and it is an order-of-magnitude estimate, not an exact count. As of November 2026 standard chess has not been solved, and no practical computer can search the whole tree of possible games. Ratings give another kind of number; the Elo rating system was made by Arpad Elo, a physics professor and chess master; a player rated 100 points higher than an opponent is expected to win about 64 percent of their games; a grandmaster norm needs a performance rating of 2600 or more in a nine-round FIDE tournament. FIDE was founded in 1924 in Paris, and its motto is Latin, Gens una sumus, which means "We are one family".

Those ideas have changed over time; a Spanish priest named Ruy Lopez, one of the first chess masters, published his analysis of an opening in 1561. In 1749 the French master Francois-Andre Philidor published Analyse du jeu des Echecs, which held the line "The pawns are the soul of chess". Some players of the 1920s tried to control the center with pieces instead of only filling it with pawns; this idea is called hypermodernism; a 13th-century Spanish book of games said chess was a nobler and more honoured game than dice or backgammon. In the late 1400s, new rules had made the queen by far the most powerful piece on the board, and the new game soon replaced the older, slower one.

Mikhail Botvinnik trained three future world champions, Karpov, Kasparov and Kramnik, and he is considered one of the fathers of computer chess. Steinitz had no equal at positional play, which means building up small advantages. Capablanca's endgame skill was considered the greatest the world had ever seen; a passed pawn grows stronger as fewer pieces are left on the board, and in the endgame the king often steps into the center or forward to support it. Some positions show how strange the rules can be. Zugzwang is a German word that means "a compulsion to move", a position in which any move a player makes leaves them worse off. In some positions it would help a player to skip a turn, but the rules do not allow that.

Machines reached the top by different roads. Deep Blue could evaluate 200 million chess positions a second, using 32 processors, and it beat Garry Kasparov in New York in May 1997. In 2017 AlphaZero was given only the rules of chess and learned by playing against itself. Stockfish is a free, open-source chess engine developed by a community of programmers. As of November 2026 it is the highest-rated engine on the computer chess rating list. The game keeps inventing itself. Chess960 is a variant that Bobby Fischer advocated; the pieces start in one of 960 possible setups, and the rules are mostly the same. In Chess960 the king must start between the two rooks, and each side's bishops must be on opposite-colored squares. Carlsen won four more world championship matches after 2013, then in 2023 chose not to defend the classical title. On December 12, 2024, 18-year-old Gukesh Dommaraju of India beat Ding Liren of China in Singapore to become the youngest world chess champion.

Words to know

• hypermodernism: new center idea
• zugzwang: forced bad move
• variant: changed version
• opening: first moves
• engine: chess program