Estonian chess grandmaster, three times chess champion of the U.S.S.R., three times European champion, and a member of the winning Soviet team at seven world Chess Olympiads.

Keres began to learn chess at the age of 4 by watching his father, and he played chess publicly at age 13. While he was still in his teens, Keres won prizes in tournaments and in 1934 won the Estonian championship. Although he studied mathematics and pursued journalism, he eventually turned to a full-time career in chess. He won the U.S.S.R. championship in 1947, 1950, and 1951 and entered several major international tournaments, including the 10th through the 15th Chess Olympiads (1952–62). Although he never captured the world championship, Keres won more than a score of international tournaments after World War II, defeating, among others, Mikhail Botvinnik (Botvinnik, Mikhail Moiseyevich), Tigran Petrosyan (Petrosyan, Tigran Vartanovich), and Boris Spassky (Spassky, Boris Vasilyevich), all of whom were world champions.

Keres wrote The Theory of Chess Openings: Open Openings, parts 1–2 (1949–52), with a third part entitled French Defense (1958); his last book was Practical Chess Endings (1974).