Cargo

Air cargo is commonly known as freight. There are many firms which collect freight from a shipper and deliver it to the customer such as Nightfreight or UPS. Aircraft were first used for carrying mail as cargo in 1911, but eventually manufacturers started designing aircraft for freight as well. There are many commercial aircraft suitable for carrying cargo such as the Boeing 747 and the bigger An-124, which were purpose built to be easily converted to a cargo aircraft. Such very large aircraft also employ quick loading containers known as ULDs much like containerized cargo ships.
Most nations own and utilize large numbers of cargo aircraft such as the C-17 Globemaster III, for airlift logistics needs of such operations.
Trains are capable of transporting large numbers of containers which have come off the shipping ports. Trains are also used for the transportation of steel, wood and coal. Trains are used as they can pull a large amount and generally have a direct route to the destination. Under the right circumstances, freight transport by rail is more economic and energy efficient than by road, especially when carried in bulk or over long distances.
The main disadvantage of rail freight is its lack of flexibility. For this reason, rail has lost much of the freight business to road transport. Rail freight is often subject to transshipment costs since it must be transferred from one mode to another in the chain; these costs may dominate and practices such as containerization aim at minimizing these. Many governments are now trying to encourage more freight onto trains, because of the environmental benefits that it would bring; rail transport is very energy efficient.