ABSTRACT
In this chapter, the authors set up the basic physical frameworks in which nonlinear wave propagation will take place. They recall the basic fundamentals of fluid dynamics (including dissipation), ideal magnetofluid dynamics, and plasma physics (limited to the two component fluid model). The structure of liquids is much more compact than that of gases. When a fluid is electrically conducting and is placed in an external magnetic field there is an interplay between electromagnetic and hydrodynamic effects. The pressure depends strongly on the density and in some cases the dependence of pressure on entropy is negligible. Therefore the flow must be described by the equations for the electromagnetic field coupled to the fluid motions.
