The history of Operations Management began around 5000 B.C. when Sumerian priests developed the ancient system of recording inventories, loans, taxes, and business transactions. It is a field that can, at times, be misunderstood because of its multidisciplinary nature. Operations management handles various strategic issues including determining the size of manufacturing plants and project management methods, and implementing the structure of information technology networks. It approaches the acquisition of materials and use of labor in a timely, cost-effective manner to deliver customer expectations. Inventory levels are monitored to ensure excessive quantities are on hand.