A stock-keeping unit (SKU) is a unique code that a retailer assigns to a product to manage inventory, flow, and sales. Businesses often use it in the form of an 8-digit alphanumeric number to identify products internally.

For their goods and services, businesses develop several SKUs. For example, a store that sells shoes creates internal SKUs and indicates product data such as color, size, style, price, manufacturer, and brand to ensure it is accurately tracked. 

An SKU is different from barcodes. While barcodes should be assigned to all like products regardless of where they are sold, SKUs are unique to a business or seller and assigned to a product to identify the price and other products related information.