Plasma astrophysics studies electromagnetic processes and phenomena in space, mainly the role of forces of an electromagnetic nature in the dynamics of cosmic matter. Two factors are specific to the latter: its gaseous state and high conductivity. Such a combination is unlikely to be found under natural conditions on Earth; the matter is either a non-conducting gas (the case of gas dynamics or hydrodynamics) or a liquid or a solid conductor. By contrast, plasma is the main state of cosmic matter. It is precisely the poor knowledge of cosmic phenomena and cosmic plasma properties that explains the retarded development of plasma astrophysics. It has been distinguished as an independent branch of physics in the pioneering works of Alfvén (see Alfvén, 1950).