Kanban is a scheduling system used in lean manufacturing to control work in process inventory and optimize production. It tells producers what to make, when to make it, and how much to make based on customer demand. There are different types of kanbans including raw material, work in process, and finished goods kanbans. Kanbans work by signaling when more inventory is needed to replenish bins and keep just the right amount of materials and products flowing through the production process. The goal is smooth and efficient production without waste.