The Fields Medal is awarded every 4 years on the occasion of the International Congress of Mathematicians in recognition of outstanding mathematical achievement for existing work and showing promise of future achievement. The Fields Medal Committee is chosen by the Executive Committee of the International Mathematical Union and is normally chaired by the International Mathematical Union (IMU) President. The Committee is asked to choose at least two, with a strong preference for four, Fields Medalists, and to have regard in its choice as to represent a diversity of mathematical fields. The candidate must not have attained 40 years on January 1st of the year of the Congress at which the Fields Medals are awarded. No more than four Fields Medals are awarded at one time. The award consists of gold medal bearing the profile of Archimedes and a cash amount of CAD 15,000. Any person can receive Fields Medal only once, and cannot previously have received any other IMU award (Nevanlinna Prize, Gauss Prize, Chern Medal, and Leelavati Prize).