This book presents an overview of the current understanding of the physics of zero-dimensional semiconductors. It concentrates mainly on quantum dots of wide-gap semiconductors, but touches also on zero-dimensional systems based on silicon and III-V materials. After providing the reader with a theoretical background, the author illustrates the specific properties of three-dimensionally confined semiconductors, such as the size dependence of energy states, optical transitions, and dephasing mechanisms with the results from numerous experiments in linear and nonlinear spectroscopy....