This book provides an overview of the physics of condensed matter systems. Assuming a familiarity with the basics of quantum mechanics and statistical mechanics, the book establishes a general framework for describing condensed phases of matter based on symmetries and conservation laws. After surveying the structure and properties of materials with different symmetries, it explores the role of spatial dimensionality and microscopic interactions in determining the nature of phase transitions. Particular attention is given to critical phenomena and renormalization group methods.