  A concise review of the notions of elliptic functions, modular forms, and
theta-functions is provided, devoting most of the paper to applications to
Conformal Field Theory (CFT), introduced within the axiomatic framework of
quantum field theory. Many features, believed to be peculiar to chiral 2D (=
two dimensional) CFT, are shown to have a counterpart in any (even dimensional)
globally conformal invariant quantum field theory. The treatment is based on a
recently introduced higher dimensional extension of the concept of vertex
algebra.
