What is a packing slip?

A packing slip travels with the box and answers one question at the dock: what does the shipper claim is in this shipment? It lists items and quantities, usually with the order or PO reference, and sometimes notes backordered lines shipping separately. It is not an invoice; it carries no prices and creates no payment obligation. It's the shipment's manifest. The receiving discipline it enables is simple: count what's physically in the box, compare against the slip, then compare the slip against your PO. Those are two different checks. The box matching the slip means the shipper packed what they claimed. The slip matching the PO means they shipped what you ordered. A shipment can pass the first and fail the second, like when a supplier substitutes a part number and the slip cheerfully documents the substitution nobody approved. Where teams trip: the signature shortcut. A driver is waiting, someone signs the slip without counting, and the slip goes in a drawer. That signature just confirmed receipt of whatever the supplier claims, and the short-ship discovered two weeks later is now your word against a signed document. Count before signing on anything that matters, note discrepancies on the slip itself, and record the received quantities against the PO while the box is still open.