Deep Blue was a supercomputer designed by IBM specifically for the purpose of playing chess. The computer distinguished itself in 1997 by beating Garry Kasparov, one of the top chess players in the world. Although Deep Blue was retired after this match, the match laid the groundwork for increasingly sophisticated chess computers and programs, and many chess players now utilize chess software as a learning and practice tool to keep their games sharp.
The inspiration for Deep Blue came to Feng-Hsiung Hsu in 1985. Hsu started to develop a computer which he called Chiptest, later bringing the idea to IBM when he joined to company in 1989. At first the resulting computer was code-named Deep Thought, and jokers at IBM later proposed “Deep Blue,” a melding of “Deep Thought” and “Big Blue,” IBM's nickname.
This supercomputer was specifically designed for the purpose of playing chess, with the developers taking a hardware based approach, rather than focusing on software like that used in modern chess programs. Like other supercomputers, Deep Blue was incredibly powerful for its time, with 1.4 tons of hardware to back up a chess program written in C and capable of calculating up to 200 million potential positions every second. Deep Blue could see up to 40 moves, or plies as they are known in the chess world, ahead.
The computer drew its strategy from an extensive record of chess games played by Masters and Grand Masters. Using the records of these games, Deep Blue could consider a wide range of possible moves, gambits, and strategies which would potentially allow it to dynamically respond to moves made by an opponent. Deep Blue also improved its game by playing several matches with chess Masters, with programmers learning from the computer's mistakes.
Deep Blue's first match against Kasparov took place in 1996, and Kasparov won the match. The 1997 match featured a substantially updated Deep Blue, however, and the computer integrated adaptations from its experiences in the previous match against Kasparov. Deep Blue won the match, taking two games outright to Kasparov's one and gaining another point and a half from three draws, for a total of three and a half to two and a half.
Kasparov later decried the 11 May 1997 match against Deep Blue, arguing that the computer displayed such depth of intelligence that humans must have intervened during the games to help Deep Blue win. He demanded a rematch, which IBM refused, and the issue became a topic of some controversy in the chess and computing communities. Some knowledgeable chess critics pointed out that Kasparov's strategy in the 1997 match was extremely conservative and very out of character for him, suggesting that he might have won if he had played with his usual aggressive, dynamic style.