The purpose of this book is to give an up-to-date presentation of architectures and technologies for wafer-scale integration. As such, it is an overview of the work of the leading research centers active in this area, and an outline of expected evolution and progress in the subject. New technological solutions are envisioned; while the use of optical technologies for interconnections promises to overcome one of the main restrictions to architectures on a wafer, the extension of quick-prototyping solutions to the wafer dimension allows the introduction of wafer-scale systems in educational environments as well as in applications where a quick result and limited production would make traditional silicon solutions unacceptable. Regarding architectures and their applications, three different lines of approach can be identified. Evolutive solutions are proposed, mainly concerning array architectures and restructuring techniques. Innovative architectures are presented, several papers dealing with neural nets. There are also architectures designed not just for experimental reasons but for industrial production. Overall, non-numerical applications predominate.