Pierre de Fermat (17 August 1601 – 12 January 1665) was a French lawyer at the Parlement of Toulouse, southern France, and a mathematician. Many people see him as the father of modern calculus.
His method of finding the biggest and smallest ordinates of curved lines also makes him a contributor to differential calculus, which was not known at that time. His studies in the theory of numbers give him the rank of the founder of the modern theory. He also made notable contributions to analytic geometry, probability and optics.