  We present short review of two methods for obtaining functional equations for
Feynman integrals. Application of these methods for finding functional
equations for one- and two- loop integrals is described in detail. It is shown
that with the aid of functional equations Feynman integrals in general
kinematics can be expressed in terms of simpler integrals. Similarities between
functional equations for Feynman integrals and addition theorem for Abel
integrals are shortly discussed.
