Kanban - "signal card," a communication method used in the pull system indicating that the system is ready to receive the input. Most often this is done using a card as the indicator but it could also be an empty chart or some other indicator.
Kanban is a tool used to manage material flow in a process and is integral to pull production systems.
Some will say a Kanban must be a card, or similar, indicator (that you would attach to a board but has no actual function [say an empty cart]). But we do not agree. Others would create a computerized Kanban system and others would say that is not allowable. We think that is not normally wise but think such a system could be considered Kanban. The resouces below offer addition details on Kanban and it is and is not.
From This Too is a Kanban by Jon Miller: