The Collège de France is organized into Chairs. They cover a vast range of disciplines : from mathematics to the study of great civilizations, physics, chemistry, biology and medicine, philosophy and literature, social sciences and economics, prehistory, archaeology and history... A professor appointed to a statutory chair at the Collège de France may hold it for the rest of his or her career. A small number of annual chairs, all thematic or international, welcome visiting professors on a temporary basis.