A Stock Keeping Unit (SKU) is an identification designation such as a number or code
for an individual item in a retailer's assortment.The Stock Keeping Unit (SKU) enables the unique identification of a product and is important for a retailer's inventory management. Data warehouse applications record and monitor inventory changes from each individual Stock Keeping Unit. Brick-and-mortar retailers have a more limited number of SKU units than online retailers. While small brick-and-mortar stores sometimes have as few as 800-1200 SKUs, e-commerce retailers like Amazon have hundreds of thousands of stock keeping units (SKUs) through the long-tail strategy approach and through external partnerships.