Upon looking for a very credible bibliographical source, I came across the Hutchinson Dictionary of Scientific Biographies. The biography gives a fairly brief overview of the entire life of Pierre de Fermat. It begins giving a brief overview by skipping most of his early life, only really acknowledging that he was a French lawyer and magistrate who treated mathematics as a hobby, but contributed greatly to a variety of mathematical fields. Pierre de Fermat was born on August 20, 1601 in Beaumont de Lomagne. This biography does not try to exactly pinpoint where he received his early education from. It simply says he received a "classical education locally". After receiving his early education, believed to be between the ages of 20 and 30 he relocated to Bordeaux where he may have studied at the University of Toulouse. While here, Fermat was introduced to mathematics discovered by François Viète. Fermat became especially interested in the field of Number Theory, which is where many of his well known contributions came from. However, his studies at school were not devoted to the field of mathematics. Instead he studied law, and at the age of 30 received a bachelor's degree in civil law from the University of Orleans. After maintaining a legal practice in Toulouse, he was moved higher over time by parliament and finally ended as the king's counselor until 1665.
Fermat's accomplishments in mathematics may have came from an attack of the plague because after he suffered through the illness, much of his time was dedicated tot his study. Through his own works and working to redo some early Greek work. While he did not publish his works, he did create and publish problems for other mathematicians to solve. In fact, Fermat is most likely known for "Fermat's last theorem" which was the final one to be proved and was done so in 1993 by Andrew Wiles. The theorem states:
Fermat's techniques led rise to his interest in Geometry, from which he provided much insight into Analytic Geometry which was discovered at the same time by René Descartes. From Analytic Geometry Fermat proceeded to move towards curves and found a method of finding the tangent line to equations. The results he achieved were verified due to the same result being obtained from what is modern day Calculus. Fermat also worked with Blaise Pascal to develop the foundation of probability theory, mainly the probability of two independent events occurring. Fermat also provided some insight in Optics despite conclusions disagreed with by Descartes, Fermat produced "Fermat's principle".
Fermat died on January 12, 1675 in Castres.
"Fermat, Pierre De (1601-1675)." The Hutchinson Dictionary of Scientific Biography. Abington: Helicon, 2013. Credo Reference. Web. 26 April 2014.