This book focuses on three main themes. Theme one - advances in basic science. Point defects, dislocations, doping, the properties of nitride alloys with a special emphasis on localization phenomena and GaAsN alloys (which are very promising for long-wavelength emitters), transport and optical properties are also featured. Theme two - growth and growth-related issues. Significant advances have been made in understanding/improving all major nitride growth techniques (MBE, MOCVD, HVPE). Techniques such as ELOG and the development of bulk-like substrates are receiving attention as methods to reduce the number of dislocations. Theme three - devices. Tremendous progress has been reported in device design and optimization, and also in understanding device processing issues such as p-contacts, laser lift-off, and etching. Overall, the book offers a broad exchange of scientific knowledge and technical expertise. Topics include: molecular beam epitaxy and growth kinetics; point defects and doping; light emitters; nitride alloys and lateral epitaxy; quantum wells; transport and optical properties; vapor phase epitaxy; extended defects; electronic devices and processing.