Container is a standardized reusable steel box used for the safe, efficient and secure storage and movement of materials and products within a global containerized intermodal freight transport system. “Intermodal” indicates that the container can be moved from one mode of transport to another (from ship, to rail, to truck) without unloading and reloading the contents of the container.
Lengths of containers, which each have a unique ISO 6346 reporting mark, vary from 8 to 56 feet (2.438 to 17.069 m) and heights from 8 feet (2.438 m) to 9 feet 6 inches (2.896 m). There are approximately 17 million intermodal containers in the world of varying types to suit different cargoes. Aggregate container capacity is often expressed in twenty-foot equivalent units (TEU) which is a unit of capacity equal to one standard 20 ft × 8 ft (6.10 m × 2.44 m) (length × width) container.
For air freight the alternative and lighter IATA-defined unit load device is used. Non-container methods of transport include bulk cargo, break bulk cargo and tank cars, tank trucks or oil tankers used for liquids or gases.