Muda (無駄) is a Japanese word meaning "futility; uselessness; wastefulness",[1] and is a key concept in the Toyota Production System (TPS) as one of the three types of deviation from optimal allocation of resources (the others being mura and muri).[2] Waste reduction is an effective way to increase profitability. Toyota adopted these three words beginning with the prefix mu-,[3] which in Japan are widely recognized as a reference to a product improvement program or campaign.