Quantum Fluids -- Helium — General Properties -- Superfluid 4He — Helium II -- Normal-Fluid 3He -- Superfluid 3He -- Mixtures of 3He and 4He -- Solids at Low Temperatures -- Phonons -- Conduction Electrons -- Magnetic Moments — Spins -- Tunneling Systems -- Superconductivity -- Principles of Refrigeration and Thermometry -- Cooling Techniques -- Thermometry.This book provides a concise but thorough introduction to important phenomena of low-temperature physics. It is ideally suited as a textbook for advanced undergraduates but will also be valuable for graduate students, scientists and engineers working in this field. Clear explanations of both theoretical and experimental approaches coupled with carefully selected problems will enable students to gain a firm understanding of even the most recent research developments.