Book excerpt: This book covers all aspects of the technology and physics of infrared, visible-spectrum, and white-light-emitting diodes (LEDs) made from III–V semiconductors. The book reviews elementary properties of LEDs such as the electrical and optical characteristics. The author also reviews advanced device physics including high-efficiency device designs, light extraction, radiative and non-radiative recombination dynamics, spontaneous recombination in resonant-cavity structures, and packaging. The reader is introduced to areas related to visible-spectrum and white LEDs such as human vision, photometry, colorimetry, and color rendering. Application of infrared and visible-spectrum LEDs in silica fiber, plastic fiber, and free-space communication is discussed. Extensive semiconductor material data, device design data, and analytic formulas governing the operation of LEDs are provided. Exercises and illustrative examples are used to reinforce the topics discussed. An introductory chapter reviews the historical developments and milestones of LED research and development. This textbook will be of interest to scientists and engineers working on LEDs, notably in lighting, illumination and signage, and also to graduate students in electrical engineering, applied physics, and materials science.