This lecture covers the principles of thermal energy harvesting, thermoelectrics, thermoelectric power generation, material properties, and efficiency properties. It explains the importance of the Seebeck effect, series connections, and the figure of merit in maximizing power generation efficiency. The lecture also discusses examples of architectures for thermal energy harvesting and microfabricated examples of thermoelectric power generation. It concludes with a comparison of different conversion principles for vibrations and their applications in various systems.