The Drude Theory of Metals. The Sommerfeld Theory of Metals. Failures of the Free Electron Model. Crystal Lattices. The Reciprocal Lattice. Determination of Crystal Structures by X-Ray Diffraction. Classification of Bravais Lattices and Crystal Structures. Electron levels in a Periodic Potential: General Properties. Electrons in a Weak Periodic Potential. The Tight-Binding Method. Other Methods for Calculating Band Structure. The Semiclassical Model of Electron Dynamics. The Semiclassical Theory of Conduction in Metals. Measuring the Fermi Surface. Band Structure of Selected Metals. Beyond the Relaxation. Time Approximation. Beyond the Independent Electron Approximation. Surface Effects. Classification of Solids. Cohesive Energy. Failures of the Static Lattice Model. Classical Theory of the Harmonic Crystal. Quantum Theory of the Harmonic Crystal. Measuring Phonon Dispersion Relations. Anharmonic Effects in Crystals. Phonons in Metals. Dielectric Properties of Insulators. Homogeneous Semiconductors. Inhomogeneous Semiconductors. Defects in Crystals. Diamagnetism and Paramagnetism. Electron Interactions and Magnetic Structure. Magnetic Ordering. Superconductivity. Appendices.