Some aspects of the functor K_2 of fields

Abstract

A review of the connections between K_2 of a field and universal central extensions, quadratic forms, central simple algebras, differential forms, abelian extensions, abelian coverings, explicit reciprocity laws, special values of zeta functions, and special values of L-functions. No proofs, minimal bibliography.

Final version. To appear in the Journal of the Ramanujan Mathematical Society