Lean

Lean is a systematic approach to organizing production and workflows that aims to maximize value to the customer while minimizing waste. The concept originated with the Toyota Production System in the postwar period and was popularized in the 1990s by James P. Womack, Daniel Jones, and Daniel Roos in The Machine That Changed the World.

Lean rests on five guiding principles: specify value from the customer’s perspective; map the value stream and remove waste; create continuous flow; implement a pull system; and pursue perfection through ongoing improvement. Central ideas include eliminating muda, the wasteful activities that do not add value, and kaizen, the discipline of continuous incremental improvement. Respect for people underpins Lean culture.

Common Lean tools and methods include 5S workplaces, Kanban scheduling, Just-in-Time production, Jidoka (automation with human oversight), SMED for rapid changeovers, Poka-yoke error-proofing, and standard work. Techniques such as value-stream mapping help visualize processes to identify bottlenecks and waste. Lean emphasizes visual management, cross-functional teams, and frequent problem-solving.

Although rooted in manufacturing, Lean concepts have been applied to services, software development (Lean software development), product development, healthcare, and logistics. Related movements include Lean management and Lean Startup, which adapts lean thinking to entrepreneurship. Critics note challenges in implementation, potential overemphasis on waste reduction at the expense of innovation, and risks of under-resourcing or misapplication.