A stock keeping unit (SKU) is an alphanumeric code that’s assigned to each of your products, indicating style, size, color, and pricing (among other key attributes). As its name suggests, SKUs help ecommerce retailers keep track of their stock levels internally; if an item comes in multiple sizes or colors, every variation will have its own UPC barcode so it’s easier to locate within your supply chain or fulfillment center. Each unique SKU can be tailored to represent whatever your customers or vendors typically ask about with regards to your product catalog.