Textbook in PDF format This 2nd edition of the book focuses on the properties of stationary states in chaotic systems of particles or fluids, setting aside the theory of how these states are achieved. The second edition has been thoroughly revised and includes numerous corrections. It incorporates recent findings, with particular emphasis on the equivalence between irreversible and reversible equations. The ongoing debate over reversibility and irreversible behavior is frequently discussed. The book seeks to unify the study of stationary nonequilibrium states with that of equilibrium states, using the paradigm offered by the simplest chaotic systems, specifically Anosov systems