Many books have been written about lean manufacturing. But no matter what aspect of Toyota's methods the authors are talking about—the production system as a whole, the JIT concept, the rapid changeover process, the product development system—they are all about people first and foremost. Without professional, conscientious and passionate staff, neither Toyota nor the other companies that follow in its footsteps would be successful. Educating, training and promoting people is the basis on which all the tools, methods and rules that make up the essence of lean manufacturing are based. The book talks about Toyota's unique personnel management system, which is largely built on TWI (Training Within Industry) technology developed in the USA.