This review discusses the principal physical mechanisms responsible for direct electromagneticacoustic conversion in ferromagnets. It is shown that in a wide range of frequency, magnetic field, and temperature ultrasound is generated via the inductive and magnetoelastic interactions. In the latter mechanism features are observed that are due to the displacement of domain walls and spin flip, and are also observed at various phase transitions. A detailed comparison of the theory of electromagnetic excitation of ultrasound with experimental data obtained for 3d and 4f magnets also showed that this phenomenon can be used as a precise method of constructing magnetic phase diagrams of magnets and determining their homogeneous and inhomogeneous exchange interaction constants, and the magnetic anisotropy and magnetostriction constants.