a code number, typically used as a machine-readable bar code, assigned to a single item of inventory. As part of a system for inventory control (operations research), the SKU represents the smallest unit of a product that can be sold from inventory, purchased, or added to inventory. Applied to wholesale, retail, or production operations, the SKU can assist in monitoring transactions, tracking customer spending patterns, controlling inventory and purchasing, and providing information about pricing. (See also UPC.)