This concise introduction to the key concepts and tools of modern statistical mechanics is self-contained. Combining analytical and numerical techniques, it also covers advanced topics such as non-relativistic quantum field theory. After introducing classical analytical techniques, the authors present important numerical methods and a diverse range of applications. Quantum statistical mechanics is then analyzed and applied to topics in astrophysics and cosmology. Combining the authors´ many years´ experience of teaching courses in this area, this textbook is ideal for advanced students in physics, chemistry and mathematics.