Lean is an operating philosophy that maximises customer value by systematically removing waste — activities the customer won’t pay for. The method originates in the Toyota Production System (TPS).
Lean rests on five principles: define value from the customer’s point of view, map the value stream, create flow, establish pull and pursue perfection through continuous improvement. The tools — 5S, VSM, SMED, kanban — are means, not the goal.
The most common misconception is treating Lean as a project with an end date. Lean is a way of running a business, and it only lasts if management changes its own behaviour — not just the employees’.