Kanbans are pull signals used to connect processes that are not capable of continuous flow, tying two processes together like an invisible conveyer. Kanban systems can be electronic, card-based and visual. Kanbans are inspired by the supermarket principle:

1. Customer demand goes to the earlier process (supermarket) to acquire the required products in the exact quantity needed at the time of need
2. The earlier process immediately replenishes the shelves with the quantity required (restocking the shelves) from the local inventory
3. Replenishment of the shelves triggers an order to the supplier to replenish the local inventory