The core of lean manufacturing, kanbans use the “pull” system to prevent waste by creating a cyclical relationship between the consumer, supplier, and manufacturer. The user of a material requests or "pulls" material from the supplier, as they need it. They do this using some form of notification.  Product consumption information is sent from the user upstream to the supplier so that consumed materials can be restocked as needed. Ultimately, this eliminates overproduction and waste from the previous unnecessary use of materials and machinery.

Roughly translated as "sign" or "visual card," a kanban can be any device that communicates the need for an item. Kanbans ensure that only what is needed is ordered and in the proper amount.

The first kanbans, signboards, were used to transfer inventory information between production processes. Taiichi Ohno, former vice president of Toyota Motors, designed the concept in the mid 1950s after observing the operating system of an American supermarket. He was taken with the concept of only supplying what was needed, when it was needed, and how greatly this prevented unnecessary production and waste.

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