The  Foundation  series  is a  science fiction  book series written by American author  Isaac Asimov . For nearly thirty years, the series was a trilogy:  Foundation ,  Foundation and Empire ,  Second Foundation . It won the one-time  Hugo Award  for "Best All-Time Series" in 1966. [1] [2]  Asimov began adding to the series in 1981, with two sequels:  Foundation's Edge ,  Foundation and Earth , and two prequels:  Prelude to Foundation ,  Forward the Foundation . The additions made reference to events in Asimov's  Robot  and  Empire  series , indicating that they were also set in the same fictional universe. read online --->> here   download ---->> here