Cargo is goods carried by a ship, aircraft, truck, or other vehicle from one place to another. Grain in a ship’s hold. Packages in a delivery van. A satellite on top of a rocket. Cargo is the reason the vehicle made the trip.

Cargo comes from outside the vehicle, travels inside it, and goes to a destination outside it. This is what separates cargo from everything else aboard. Fuel is consumed during the trip — not cargo. Equipment is used to operate the vehicle — not cargo. Ballast exists to keep the ship stable — not cargo. Cargo is the payload: the thing being delivered.

The carrier holds cargo in custody. The cargo belongs to the shipper; the carrier is responsible for getting it there intact. Under the Hague-Visby Rules, the carrier has a duty to “properly and carefully load, handle, stow, carry, keep, care for, and discharge the goods.” Damage in transit is the carrier’s problem. This custody relationship — possession without ownership — is a bailment.

Cargo is not transformed in transit. What gets loaded is what gets unloaded. A carrier that systematically changes its cargo is a factory, not a carrier. Perfect carriage means the cargo arrives identical to how it left.

Passengers are not cargo. Passengers are parties to the contract of carriage — they have agency, they can refuse, they can complain. A passenger’s luggage is cargo. The passenger is not.

The word comes from Spanish cargo (“load, burden”), from cargar (“to load”), from Late Latin carricare. The same root gives us “charge” — to load something with weight or responsibility.

In rocketry, what counts as cargo depends on your level of zoom. The Falcon 9’s payload is the Dragon capsule. The Dragon’s cargo is the supplies inside. At each level, the outer vehicle is the carrier and the inner stuff is the cargo.