Pierre-Louis Lions is a French mathematician born in Grasse in 1956, laureate of the Fields Medal in 1994. He entered the Ecole Normale Supérieure in 1975. He dedicates himself to research in applied mathematics and obtained his habilitation in 1979 in Pierre and Marie Curie University. From 1979 to 1981, he was a researcher at the CNRS and then became professor at the University of Paris-Dauphine in 1981 and professor of mathematics applied at the Ecole Polytechnique from 1992 to 2016. He was appointed professor at the Collège de France in 2002, holder of the chair "Partial and partial derivative Equations". Applications". Among his works, he was the first mathematician to give a solution to Boltzmann's equation and introduced, in collaboration with Michael Crandall, the concept of viscosity solutions whose fields of application are multiple. In recent years, in collaboration with Jean-Michel Lasry, he has introduced and developed the theory of medium field games and its applications in particular to economics and finance. In addition to the Fields Medal, he has received numerous awards, he is Doctor Honoris Causa of several universities and member of numerous academies. He is Commander of the Legion of Honor. His collaborations with the world of the company are many and varied as scientific advisors, administrator, responsible for research contracts or patronage actions, founder of MFG Labs Start-up, now a subsidiary of Havas Media. He has practiced and has many collective responsibilities. He has also trained many researchers including Cédric Villani (Fields Medal), B. Perthame (INRIA Grand Prix), N. Masmoudi (Fermat Prize), C. Le Bris (Blaise Pascal Prize), M. Esteban (President of ICIAM).