Crystal structure. X-ray scattering and other structural experimental techniques. Complex systems: liquids, superlattices, quasicrystals. Electronic structure. Bloch theorem. Quasi-free electrons and tightly bound electrons. Fermi surface. Density of states. Van Hove singularities (Electronic Topological Transitions). Tight-binding model. Effective mass. Phonons. Specific heats. High-Tc superconductors. Graphene.