This lecture covers the Drude model, charge carrier scattering at imperfections, the relation between relaxation time and conductivity, and temperature-dependent conductivities of different materials. It explains how imperfections in real crystals induce collisions, the assumptions of the Drude model, and the electrical conductivities of metals, semiconductors, alloys, and insulators. Additionally, it discusses Ohm's law in the Drude model, temperature-dependent conductivities, and the behavior of different substances at varying temperatures.