Vladimir Drinfeld, at just 20 years old, formulates and proves in 1974 a version of the Langlands program for the group GL(2) over function fields of positive characteristic, introducing what are today known as Drinfeld modules — geometric objects analogous to elliptic curves but adapted to this arithmetic setting. The work opens one of the most fertile lines of research in late-20th-century arithmetic geometry, with later developments leading, among other results, to Laurent Lafforgue's work (Fields Medal 2002) on the general GL(n) case. Drinfeld received the Fields Medal in 1990.