Book excerpt: This book deals with the topic of biomechanical biofeedback systems and applications that are primarily aimed at motor learning in sports and rehabilitation. It gives a comprehensive tutorial of the concepts, architectures, operation, and exemplary applications of biomechanical biofeedback systems. A special section is dedicated to various constraints in designing biomechanical biofeedback systems. The book also describes the technologies needed for the adequate operation of biofeedback systems, such as motion tracking, communication, processing, and sensor technologies. In regard to technologies, the emphasis is on the assurance of the requirements of the real-time system operation. The application focus is on the usage in sport and rehabilitation, particularly in the field of accelerated motor learning and injury prevention. We include several examples of operational (real-time) biofeedback applications in golf, skiing, and swimming. The book is in the first place intended for the professional audience, researchers, and scientists in the fields connected to the topics of this book.