I have only recently (eeee! sacrilege!) discovered Mr Asimov and his delightful ability to create wonder. The man who came up with the Three Laws of Robotics (as he is fond of reminding one ad nauseum), he is a brilliant writer of all things science fiction, and also dabbled a little with fantasy, would you believe.
Of course, he is most famous for his Foundation trilogy, and the other books that he subsequently wrote in the same vein: Foundation and Empire; Foundation amd Earth; Prelude to Foundation; and Forward to Foundation, which was completed barely weeks before his death. He also wrote numerous short stories, the most famous of which involved the aforesaid Three Laws (I think I could quote them by rote now) and introduced the concept of robots that, unlike most other conceptions, would not suddenly turn on the human race and start destroying the world just for fun. Apart from such famous short stories as Nightfall, later turned into a book with Robert Silverberg, and Robbie, the first robot story, he also came up with numerous amusing fantastical concepts and wrote several tomes of learned essays on various topics. The man was a mathematical genius who also enjoyed the art of humour (and wrote several joke books). And if you want a really good take-off of the Foundation concept, read Terry Pratchett's The Dark Side of the Sun, which has a robot named Isaac even...
Foundation
The whole basis of "The Foundation" is a mathematical science called psychohistory; a means of predicting the future through probability calculations. The idea is that human civilisation, on its billions of planets in the Galaxy, can be kept in a stable steady-state of benefit to every one through the use of tiny adjustments at the margin of things. It is psychohistory that enables the proper use of these adjustments to reality - what to do, and when and how to do it. It's an interesting proposition. The earlier books, most particularly the trilogy and the books that immediately follow them, are concerned with the time when the Foundation is established and the members are striving to preserve it against internal and external threats. The latter books, most notably Prelude to Foundation and Forward to Foundation, are prequels and describe the rise of psychohistory's inventor and how, despite the fall of the old Empire, the Foundation is established on far planets to wait for the time when it can renew human civilization and maintain peace and plenty in the Galaxy.
I have read the two prequels, but haven't got my hands on the original trilogy yet... something to look forward to, I suppose. The nice part about about the prequels is that they fill in details from the life of Hari Seldon and his granndaughter, and vaguely hint at the future trilogy.
Isaac Asimov is perhaps the most famous for his various short story collections;