In the presence of magnetic induction and electrical fields several types of discontinuities may exist in an electrically conducting fluid. These phenomena can be described by the laws of conservation of mass, momentum, and energy; Maxwell's electromagnetic equations, and Ohm's law. Those discontinuities, which can be characterized by the conditions that both the temperature and density change across them are different from zero, are called magneto-hydrodynamic shock waves. This monograph is concerned with the study of these types of discontinuities.