Stefan Banach (; 1892-1945) was an eminent Polish mathematician and university professor. A self-taught mathematical prodigy, Banach was a founder of functional analysis and of the Lwów School of Mathematics. Among his most prominent achievements was a 1932 book, Théorie des opérations linéaires (Theory of Linear Operations), the first monograph on the general theory of linear-metric space. Notable mathematical concepts named after Banach include the Banach–Tarski paradox, Hahn–Banach theorem, Banach-Steinhaus theorem, and Banach space.