Concepts about JIT?

Can you clear my concepts about JIT?

Just in time is a production strategy that helps firm to produce in correct quantity and at correct time. Thus with this strategy all kinds of inventories raw materials, work in process, finished goods and spare parts etc. can be kept to a minimum. This strategy requires carefully planning and scheduling the flow of resources throughout the production process mostly using modern and sophisticated scheduling processes. Supplies and raw materials are delivered to the production line only when required. E.g. during car manufacturing exact number of tires would be delivered only when needed.