Cargo in holds may be either packaged in crates, bales, etc., or unpackaged (bulk cargo). Access to holds is by a large hatch at the top. Ships have had holds for centuries; an alternative way to carry cargo is in standardized shipping containers, which may be loaded into appropriate holds or carried on deck.
Holds in older ships were below the orlop deck, the lower part of the interior of a ship’s hull, especially when considered as storage space, as for cargo. In later merchant vessels it extended up through the decks to the underside of the weather deck.
Some ships have built in cranes and can load and unload their own cargo. Other ships must have dock side cranes or gantry cranes to load and unload.