Daniel Quillen formulates in 1972 higher algebraic K-theory, a tool that uses geometric and topological methods — in particular, homotopy techniques — to address central problems in algebra, especially in ring and module theory. The official 1978 Fields Medal citation explicitly describes Quillen as "the principal architect of higher algebraic K-theory." The theory would become one of the most far-reaching structural tools of late-20th-century mathematics, with later connections extending as far as Vladimir Voevodsky's theory of motives. Quillen received the Fields Medal in 1978.