Isaac Asimov ( AZ-im-ov; c. January 2, 1920 – April 6, 1992) was an American writer and professor of biochemistry at Boston University. During his lifetime, Asimov was considered one of the "Big Three" science fiction writers, along with Robert A. Heinlein and Arthur C. Clarke. A prolific writer, he wrote or edited more than 500 books. He also wrote an estimated 90,000 letters and postcards. Best known for his hard science fiction, Asimov also wrote mysteries and fantasy, as well as popular science and other non-fiction.
Asimov's most famous work is the Foundation series, the first three books of which won the one-time Hugo Award for "Best All-Time Series" in 1966. His other major series are the Galactic Empire series and the Robot series, which include major works such as The Caves of Steel and The Naked Sun, both written in the mid-1950s. The Galactic Empire novels are set in the much earlier history of the same fictional universe as the Foundation series. Later, with Foundation and Earth (1986), he linked this distant future to the Robot series, creating a unified "future history" for his works.