Just-in-time manufacturing is a production method that makes and moves goods only as they are needed, holding inventory to a minimum so that parts arrive at each step of assembly just before they are used. Kiichiro Toyoda framed the idea at Toyota in the late 1930s, but the working system was built after the war by Taiichi Ohno and spread across the company's plants by the early 1960s. It reorganized modern industry around the elimination of waste — and, in doing so, made global supply chains both leaner and more exposed to shock.
Walk through a modern car plant and you will not find the mountain of parts you might expect. There is no vast warehouse of spare engines, no aisles stacked with months of steel. A finished seat reaches the line a few hours before it is bolted into the one car it was built for, in that car's exact color and trim. A dashboard shows up minutes ahead of the worker who installs it. Stock that once sat for weeks now flows through the building almost without stopping. This is not luck or tight scheduling. It is the deliberate core of a system that treats a stockpile not as safety but as waste — money frozen in place, and a cushion that hides the problems it should be forcing you to fix.