Johann Radon was born on 16 December 1887 in the city of Tetschen in the Bohemia region of Austria-Hungary (now part of the Czech Republic). He received the doctoral degree in mathematics at the University of Vienna in 1910. During his career, Radon held academic positions at several universities, including the University of Hamburg, the University of Breslau, the University of Wroclaw, and his alma mater, the University of Vienna. He died on 25 May 1956 in Vienna.
Johann Radon made important contributions in real analysis, functional analysis, the calculus of variations, and differential geometry. To students of analysis, he is best know for the Radon-Nikodym theorem which gives conditions for the existence of a density function (or derivative) of one measure with respect to another. This theorem is of fundamental importance in probability, for the existence of probability density functions and conditional expected values.