The present volume 2 covers advanced topics in theoretical solid state physics and thus ties in directly with the fundamentals. Solids in external fields or more generally in non-equilibrium and deviations from the ideal 3-dimensional crystal structure (surfaces, impurities, low-dimensional structures, quantum dots, etc.) are treated. The consideration of collective phenomena such as superconductivity and magnetism complete the presentation. The reader is assumed to have the contents of Volume 1 (electrons and phonons in ideal crystals, Bloch theorem, population number representation or 2nd quantization, electron-electron and electron-phonon interaction) as well as the basic knowledge of general theoretical physics (mechanics, electrodynamics, quantum mechanics, and statistical physics) usually available after a bachelor's degree in physics. Volume 2 is thus ideally suited for students in the master's program in physics who wish to specialize in (experimental or theoretical) solid-state physics. Addressing current topics (e.g., Kondo effect, fractional quantum Hall effect, 2-dimensional crystals such as graphene, giant magnetoresistance effect, and others) provides an optimal transition to modern research.The new edition has been completely revised, expanded with numerous exercises and existing redesigned, with the associated solutions now included in the book.