A unit load device, or ULD, (ULD) is a pallet or a container. It is used to load luggage, freight, and mail on wide-body aircraft and specific narrow-body aircraft. It allows a large quantity of cargo to be bundled into a single unit. As with other cargo transport, this leads to fewer units to load, it saves ground crews time and effort and helps prevent delayed flights. Each ULD has its own packing list (or "manifest") so that its contents can be tracked.