The premise of the series is that the mathematician Hari Seldon spent his life developing a branch of mathematics known as psychohistory, a concept of mathematical sociology. Using the laws of mass action, it can predict the future, but only on a large scale. Seldon foresees the imminent fall of the Galactic Empire, which encompasses the entire Milky Way, and a dark age lasting 30,000 years before a second great empire arises. Seldon also foresees an alternative where the interregnum will last only one thousand years. To ensure the more favorable outcome, Seldon creates a foundation of talented artisans and engineers at the extreme end of the galaxy to preserve and expand on humanity's collective knowledge and thus become the foundation for a new galactic empire.

(Source: Wikipedia)