This book traces the quest to use nanostructured media for novel and improved optoelectronic devices. Starting with the invention of the heterostructure laser, the progression via thin films to quasi zero-dimensional quantum dots has led to novel device concepts and tremendous improvements in device performance. Along the way sophisticated methods of material preparation and characterization have been developed. Novel physical phenomena have emerged and are now used in devices such as lasers and optical amplifiers. Leading experts - among them Nobel laureate Zhores Alferov - write here about the fundamental concepts behind nano-optoelectronics, the material basis, physical phenomena, device physics and systems.