Mathematical problems concerning time evolution of solutions related to nonlinear systems modelling dynamics of continuous media are of great interest both in wave propagation and in stability problems. During the last few decades many striking developments have taken place, especially in connection with the effects of nonlinearity of the equations describing physical situations.The articles in this book have been written by reputable specialists in the field and represent a valuable contribution to its advancement. The topics are: discontinuity and shock waves; linear and nonlinear stability in fluid dynamics; kinetic theories and comparison with continuum models; propagation and non-equilibrium thermodynamics; exact solutions via group methods; numerical applications.