Lean Manufacturing “Lean” is a production system consisting of manufacturing cells linked together with a functionally integrated system for inventory and production control that uses less of the key resources needed to make goods. The goal of Lean is to improve efficiency by eliminating waste in the manufacturing process and is centered on preserving value with less work.
Lean Manufacturing was developed by Toyota as part of their “Toyota Production System (TPS)”. It consist of two approaches; elimination of waste and process flow improvement. The difference between these two approaches is not the goal itself, but rather the prime approach to achieving it. The implementation of smooth flow exposes quality problems that already existed, and thus waste reduction naturally happens as a consequence. The advantage claimed for this approach is that it naturally takes a system-wide perspective, whereas a waste focus sometimes wrongly assumes this perspective. 
Key lean principles are:
- Perfect first-time quality through quest for zero defects, revealing and solving problems at their ultimate source, achieving higher quality and productivity simultaneously, teamwork, worker empowerment.
- Waste minimization by removing all non-value added activities making the most efficient use of scarce resources (capital, people, space), just-in-time inventory, eliminating any safety nets.
- Continuous improvement (reducing costs, improving quality, increasing productivity) through dynamic process of change, simultaneous and integrated product/process development, rapid cycle time and time-to-market, openness and information sharing.
- Flexibility in producing different mixes or greater diversity of products quickly, without sacrificing efficiency at lower volumes of production, through rapid set-up and manufacturing at small lot sizes.
- Long-term relationships between suppliers and primary producers (assemblers, system integrators) through collaborative risk-sharing, cost-sharing and information-sharing arrangements.
AcqLinks and References:
-  Website: Wikipedia – Lean Manufacturing
- Website: RAND Lean Manufacturing and the Defense Industry
- Website: DAU – Tutorials – Lean Production / Lean Manufacturing
- Book: The Machine that Changed the World: The Story of Lean Production by Womack, Jones and Roos