Kanban is a lean manufacturing concept used in supply chain management. It uses visual signals or cards to trigger the replenishment or production of materials or goods. At Toyota, kanban was developed to maintain improvements in production by reducing excess inventory. It works by controlling the rate of replenishment between processes through kanban cards or signals that provide permission to produce. This pull-based system allows production to be determined by actual customer demand rather than forecasts, improving inventory management and responsiveness throughout the supply chain.