A Unit Load Device (ULD) is either an aircraft pallet and pallet net combination, or an aircraft container that weigh less, meet higher safety requirements, require fewer repairs and have a lower overall environmental impact. More specifically, a ULD is used to consolidate cargo in order to assist with the loading process onto an airplane. Shippers can book a ULD container and load the ULD themselves. Then a trucker at the destination can pick up the entire ULD and deliver it to a warehouse to be deconsolidated. These ULD allow large quantities of cargo to be bundled and strapped together securely onto 1 mobile unit, so they can safely and securely be transported.

The International Air Transport Association (IATA) is responsible for rules and regulations around the use of Unit Load Devices. An airworthy ULD must be structurally capable of restraining the loads and providing adequate protection to the aircraft systems and structure during flight. It is the parts that leave the control of the airline and return after passing through many unregulated hands, as most ULD operations are outsourced to ground service providers.