A stock keeping unit, or SKU, is a distinct combination of letters and numbers assigned to a particular product sold by a business. The primary purpose a stock keeping unit is to allow effective inventory tracking and to simplify merchandising activities.
Unlike a product or part number, an SKU is established by the merchant or retailer selling the product. The number of letters and numbers in a particular SKU vary. Some SKUs have all numbers, while others have a combination of numbers and letters. Though often invisible to customers, SKUs are sometimes seen in catalogs or on company websites when customers sift through product pages.