Lean, like so many innovative ideas, products, or services, was born out of necessity. In post-World War II Japan, the founder of Toyota, Sakichi Toyoda, his son Kiichiro Toyoda, and their chief engineer, Taiichi Ohno, developed the Toyota Production System (TPS). TPS is the philosophy that still organizes manufacturing and logistics at Toyota, including the interaction with suppliers and customers. These three innovative thinkers from Toyota visited the United States and they observed the great manufacturing empire established by Henry Ford. They were, however, unimpressed. They immediately noticed that while Ford had created a monumental manufacturing machine, he had failed to address what they felt was the key issue for them – waste. They noticed that with Ford's assembly line that tasks were not spaced and timed to enhance work flow. Therefore, the process was often waiting on steps to catch up to other steps, and partially completed work often piled up. In addition, the production system in place continually created a great deal of overproduction, which led to routine shut downs and layoffs and regular restarts and rehires. Although Toyota (Toyoda) was basically unimpressed with Ford's manufacturing plant, he was very impressed with another US business – Piggly Wiggly Supermarket. They saw the benefit of only reordering and restocking goods as they were purchased from the customer. They realized that if they were to compete on the world stage in the automotive industry, they would need to apply these same principles to their operation. Thus, JIT, or just-in-time inventory was developed. To do this, Toyota reduced the amount of inventory they would need to hold only to a level that its employees would need for a small period of time, and then subsequently reorder.

Although Toyota is credited with beginning Lean Production with their Toyota Production System, the roots of “lean” date back as far as the 16^th century. In 1570, King Henry III of France watched in amazement as the Venice Arsenal built galley ships in less than an hour using continuous flow process. So, as a conceptual idea, we have known for centuries that continuous flow produces results. Other companies have taken the Toyota Production System even farther. Motorola implemented Lean Production Systems, and almost immediately noticed a decrease in wastes, an increase in productivity and quality, and an increased awareness of safety. Their efforts led to the development of Lean Six Sigma. Six Sigma basically, defines quality in degrees of sigma with six being the highest and defined as no more than 3.4 defects per one million opportunities.