Psychohistory is a fictional science from Isaac Asimov's Foundation series that combines psychology and history to predict the future behavior of large groups of people. By analyzing social trends and historical patterns, psychohistorians can forecast the actions of societies over long periods, helping to guide civilizations through crises. The main character, Hari Seldon, is the creator of psychohistory. He uses this science to foresee the decline of the Galactic Empire and establishes the Foundation to preserve knowledge and culture. Through his work, Seldon aims to shorten the impending dark age and create a brighter future for humanity.