Born in Leningrad, Soviet Union, Korchnoi defected to the Netherlands in 1976 and later resided in Switzerland for many years. Korchnoi played three matches against Anatoly Karpov. In 1974, he lost the Candidates final to Karpov, who was declared world champion in 1975 when Bobby Fischer refused to defend his title. He then won two consecutive Candidates cycles to qualify for World Championship matches with Karpov in 1978 and 1981, losing both.
Korchnoi was a candidate for the World Championship on ten occasions (1962, 1968, 1971, 1974, 1977, 1980, 1983, 1985, 1988 and 1991). He was also a four-time USSR chess champion, a five-time member of Soviet teams that won the European championship, and a six-time member of Soviet teams that won the Chess Olympiad. In September 2006, he won the World Senior Chess Championship. One of the variations of the English Opening is called Korchnoi Variation and a closed variation of the Sicilian Defense is called Korchnoi Defense.