This video is part of the course "Semiconductor Fundamentals" taught by Mark Lundstrom at Purdue University. The course can be found on nanoHUB.org at https://nanohub.org/courses/sfun or on edX at https://www.edx.org/course/semiconduc... . This course provides the essential foundations required to understand the operation of semiconductor devices such as transistors, diodes, solar cells, light-emitting devices, and more. The material will primarily appeal to electrical engineering students whose interests are in applications of semiconductor devices in circuits and systems. The treatment is physical and intuitive, and not heavily mathematical. Technology users will gain an understanding of the semiconductor physics that is the basis for devices. Semiconductor technology developers may find it a useful starting point for diving deeper into condensed matter physics, statistical mechanics, thermodynamics, and materials science. The course presents an electrical engineering perspective on semiconductors, but those in other fields may find it a useful introduction to the approach that has guided the development of semiconductor technology for the past 50+ years.