Lean Manufacturing is the production system built on eliminating waste, levelling flow, and producing to actual demand rather than to forecast. It originates in the Toyota Production System and is where most Lean tooling comes from.
Its core claim is that most of the time a product spends in a factory is spent waiting, and that reducing waiting matters more than working faster. Everything else follows: pull rather than push, small batches rather than large ones, stopping when something is wrong rather than continuing.
The tools are downstream of that idea. Value stream mapping shows where time goes, SMED makes small batches affordable, Heijunka levels the schedule, Kanban regulates flow, Jidoka and Poka Yoke keep defects from travelling. Adopted individually they are techniques; adopted together they are a system, and the difference is usually why one implementation works and another does not.
The persistent misreading is Lean as a cost-reduction programme. Cost falls as a consequence of flow, but organisations that start from headcount rather than flow generally remove the slack that made improvement possible and stall.
