This video explains what a Just In Time inventory system is.
Just In Time (JIT) is an inventory system in which the company deliberately tries to maintain very little inventory or no inventory at all. In contrast to push-based inventory systems, in which a large amount of inventory is produced and then substantial efforts are made to push inventory to customers, the JIT system is pull-based. This means that inventory is only produced in response to customer demand.
Companies using JIT significantly reduce the carrying cost of inventory but increase the risk of a stockout. Thus, it is critical that information flow very quickly throughout the organization when JIT is used. This allows the company to quickly respond to changes in customer demand and to promptly fill customer orders.