This book discusses in depth many of the key problems in non-equilibrium physics. The origin of macroscopic irreversible behavior receives particular attention and is illustrated in the framework of solvable models. An updated discussion on the linear response focuses on the correct electrodynamic aspects, which are essential for example, in the proof of the Nyquist theorem. The material covers the scaling relationship between different levels of description (kinetic to hydrodynamic) as well as spontaneous symmetry breaking in real time in terms of nonlinear dynamics (attractors), illustrated using the example of Bose-Einstein condensation. The presentation also includes the latest developments — quantum kinetics — related to modern ultrafast spectroscopy, where transition from reversible to irreversible behavior occurs.