Book excerpt: Since the early 1990s, quantum dots have become an integral part of research in solid state physics for their fundamental properties that mimic the behavior of atoms and molecules on a larger scale. They also have a broad range of applications in engineering and medicines for their ability to tune their electronic properties to achieve specific functions. This book is a compilation of articles that span 20 years of research on comprehensive physical models developed by their authors to understand the detailed properties of these quantum objects and to tailor them for specific applications. Far from being exhaustive, this book focuses on topics of interest for solid state physicists, materials scientists, engineers, and general readers, such as quantum dots and nanocrystals for single-electron charging with applications in memory devices, quantum dots for electron-spin manipulation with applications in quantum information processing, and finally self-assembled quantum dots for applications in nanophotonics.