Daniel (Dan) Jones and James P. (Jim) Womack are the founders of Lean and developed the Lean management theory that revolves around five Lean principles. They studied various companies in the automotive industry for five years and saw the huge differences between Toyota and other companies. They set out to find what made Toyota so successful and described it in their books The Machine That Changed The World and Lean Thinking. The five Lean principles guide organizations in any industry that use Lean as a method for continuous improvement.

The five Lean principles are:

1. Define value from a customer perspective. Customer value thus gives direction in what you look at in the processes: what is value-added and what is not?
2. Identify how the value stream or streams (value streams) run in your organization. That is, map all your process steps by product family and eliminate (the biggest) wastes (i.e., non-value-added activities) in your processes.
3. Create Flow whenever possible, let the service or product flow through your organization in the shortest possible lead time. Make sure products or services flow smoothly to the customer, without interruptions, by executing the value-creating steps in quick succession.
4. From push to pull: start delivering something only when there is customer demand and do not create unnecessary inventory. After all, this costs money and often comes at the expense of your flexibility and quality.
5. Strive for perfection or keep improving continuously, often you can already improve a lot by removing the three biggest wastes from your process. AND once that's succeeded you can tackle the next wastes. So you improve in several steps, not trying to achieve the perfect process all at once: this prevents your beautiful plans from becoming too complex to implement quickly. As an ideal, you try to achieve a situation where value is created for the customer without waste.

Want to know more about what is Lean? Then read this article.