  A general phenomenological theory is presented for the phase behavior of
ferromagnetic superconductors with spin-triplet electron Cooper pairing. The
theory describes in details the temperature-pressure phase diagrams of real
inter-metallic compounds exhibiting the remarkable phenomenon of coexistence of
spontaneous magnetic moment of the itinerant electrons and spin-triplet
superconductivity. The quantum phase transitions which may occur in these
systems are also described. The theory allows for a classification of these
itinerant ferromagnetic superconductors in two types: type I and type II. The
classification is based on quantitative criteria.The comparison of theory and
experiment is performed and outstanding problems are discussed.
