This fully updated second edition of The Physics of Phonons remains the most comprehensive theoretical discussion devoted to the study of phonons, a major area of condensed matter physics. It contains exciting new sections on phonon related properties of solid surfaces, atomically thin materials (such as graphene and monolayer transition metal chalcogenides), in addition to nanostructures and nanocomposites, thermoelectric nanomaterials, and topological nanomaterials, with an entirely new chapter dedicated to topological nanophononics and chiralphononics.