Passenger freighters carry containers of items such as furniture, electronics, auto parts and food, or they carry oversized or heavyweight cargo that does not fit into containers. Other ships carry mail and supplies to remote destinations.
Container or box ships carry stacks of containers 20 or 40 feet long. The containers hold television sets, household appliances and office supplies. Ships carrying containers of perishable items that need refrigeration or freezing are called "reefers." Most passenger freighters are container ships.
Large and heavy cargo includes steel and machinery. Cargo ships transport these and other items too unwieldy to fit into containers; they sometimes also transport items too small to fill a container.