Introductory Statistical Mechanics explains the ideas and techniques of statistical mechanics—the theory of condensed matter—in a simplean accessible and progressive way. The text starts with the laws of thermodynamics and basic simple ideas of quantum mechanics. The conceptual ideas underlying the subject are explained, and; the mathematical ideas are developed in parallel to give a coherent overall view. The text is illustrated with examples not just from solid-state physics, but also from recent theories of radiation from black holes and recent data on the background radiation from the cosmic background explorer.