The Lean approach to quality focuses on eliminating waste, improving efficiency, and increasing value. Lean techniques seek to increase value by improving the flow of value stream activities and reducing waste. Other Lean principles include just-in-time delivery driven by customer pull — not push — and a constant, incremental search for perfection (sometimes called kaizen).
Lean practitioners use value stream mapping to identify process steps with the greatest impact on the overall product. Then, Lean projects are created to improve those processes. The "hidden factory" is a major target for Lean programs, as practitioners seek to eliminate rework and scrap. Lean principles are often used with statistical methodologies such as Six Sigma.