JIT finds its origin in Japan, where it has been in practice since the early 1970’s. It was developed and perfected by Taiichi Ohno of Toyota, who is now referred to as the father of JIT. Taiichi Ohno developed this philosophy as a means of meeting customer demands with minimum delays. Thus, in the olden days, JIT is used not to reduce manufacturing wastage, but primarily to produce goods so that customer orders are met exactly when they need the products.

JIT is also known as lean production or stockless production, since the key behind a successful implementation of JIT is the reduction of inventory levels at the various stations of the production line to the absolute minimum. This necessitates good coordination between stations such that every station produces only the exact volume that the next station needs. On the other hand, a station pulls in only the exact volume that it needs from the preceding station.

The JIT system consists of defining the production flow and setting up the production floor such that the flow of materials as they get manufactured through the line is smooth and unimpeded, thereby reducing material waiting time.  This requires that the capacities of the various work stations that the materials pass through are very evenly matched and balanced, such that bottle necks in the production line are eliminated. This set-up ensures that the materials will undergo manufacturing without queueing or stoppage. 

Another important aspect of JIT is the use of a 'pull' system to move inventories through the production line. Under such a system, the requirements of the next station is what modulates the production of a particular station.  It is therefore necessary under JIT to define a process by which the pulling of lots from one station to the next is facilitated.

JIT is most applicable to operations or production flows that do not change, i.e., those that are simply repeated over and over again. An example of this would be an automobile assembly line, wherein every car undergoes the same production process as the one before it.

JIT has likewise been practiced successfully by some semiconductor companies. Still, there are some semiconductor companies that don’t practice JIT for the simple reason that their operations are too complex for JIT application. On the other hand, that’s precisely the challenge of JIT – creation of a production set-up that is simple enough to allow JIT.