The Foundation series is a science fiction book series written by American author Isaac Asimov. First collected in 1951, for thirty years the series was a trilogy: Foundation, Foundation and Empire, and Second Foundation. It won the one-time Hugo Award for "Best All-Time Series" in 1966. Asimov began adding new volumes in 1981, with two sequels: Foundation's Edge, Foundation and Earth, and two prequels: Prelude to Foundation, Forward the Foundation.