Before you create checkouts and orders, you'll need to define your stock keeping units (SKUs). In the retail word, a SKU is a unique set of numbers and letters used to identify, locate and track your product. They typically provide information on the most important characteristics of the item.
SKUs aren’t meant to be universal. They’re almost always unique to your business. That way they can be tailored to represent what your customers or vendors most need to know about the product.