Isaac Asimov was a Russian-born American writer and professor of biochemistry, best known for his works of science fiction and for his popular science books. He wrote or edited more than 500 books and an estimated 90, 000 letters and postcards. Asimov is widely considered to be one of the most prolific writers of all time. He is also known for his Three Laws of Robotics and the Foundation Series. Asimov's most famous work is the Foundation Series, which chronicles the fall of the Galactic Empire and the rise of a new civilization.