Condensed matter physics is an important area of current research and serves as the basis for modern electronic technology and materials science. This course starts with the structure of solids, lattice dynamics, and phonons. The electron theory of solids is described and applied to explain the properties of metals, semiconductors, dielectrics, and superconductors. Magnetic properties, optical properties, and elementary excitations in solids (plasmons, polarons, and excitons) are studied. Modern topics, including nanocrystals and photonic crystals, are discussed.