Mura (斑) is a Japanese word meaning "unevenness; irregularity; lack of uniformity; nonuniformity; inequality", and is a key concept in the Toyota Production System (TPS) as one of the three types of waste (muda, mura, muri). Waste reduction is an effective way to increase profitability. Toyota adopted these three Japanese words as part of their product improvement program, due to their familiarity in common usage. For example: If parts or material defects are found in one process, the Just-in-Time approach requires that the problem be quickly identified and corrected.