Kanban - 看板

This is the best out of numerous definitions that I'd prefer:-

Kanban, (in kanji 看板) means "visual," and ban (in Kanji 板) means "card" or "board", is a concept related to lean and just-in-time (JIT) production. It is essentially a Japanese information system for coordinating production orders and withdrawals from in-process inventory to realize JIT production. Originated from the use of cards to indicate a work station's need for additional parts. A basic kanban system includes a withdrawal kanban that states the quantity that a later process should withdraw from its predecessor, a production kanban that states the output of the preceding process, and a vendor kanban that tells a vendor what, how much, where, and when to deliver.

It was out of a need to maintain the level of improvements that the kanban system was devised by Toyota. In addition, it proves to be an excellent way in promoting continuous improvement.