packing slip definition is a document included in shipments that outlines the items inside the package. It typically includes details like the quantity of items, item descriptions, SKU numbers, and sometimes pricing or order numbers. A packing slip is used for inventory tracking, order verification, and ensuring that the correct items are included in a shipment. It is not typically used as a receipt, as it does not show prices. Packing slips are useful for both the seller and the buyer, providing a quick reference to check the contents of the package without opening it.