Kasparov-Deep Blue 1997

Kasparov-Deep Blue 1997 was a six-game rematch played in New York in May 1997. Garry Kasparov was the reigning world champion, and Deep Blue was an IBM computer built specifically to play chess. The match used standard tournament time controls, meaning slow games in which each side had hours, rather than minutes, to make its moves.

Kasparov won Game 1 and Deep Blue won Game 2. The next three games were draws, so the contest was decided in the sixth and final game. Deep Blue won it and took the match 3.5-2.5. The distinction from 1996 matters: Deep Blue won one game in the earlier meeting, but Kasparov recovered and won that match 4-2.

Deep Blue became the first computer system to defeat a reigning world champion in a match under those conditions. Its 32 processors could examine about 200 million positions per second, supported by a position-evaluation function, databases, and knowledge supplied by grandmasters. It was a specialized system with a purpose similar to a modern chess engine, meaning software that calculates and evaluates positions, not a general intelligence that understood chess as a person does.

The result mattered beyond competition. It turned a computing milestone into a worldwide public event and changed how players, journalists, and researchers discussed the balance between human judgment and machine calculation.