Containerization is a system of intermodal cargo transport using standard containers that can be loaded on container ships, freight train wagons, and trucks. There are two standard sizes, one 20 feet long and the other twice as long at 40 feet. Container capacity (of ships, ports, etc) is measured in twenty-foot equivalent units (TEU, or sometimes teu). A twenty-foot equivalent unit is a measure of containerized cargo equal to one standard 20 ft x 8.5 ft x 8.5 ft container (approximately 40.92 m3). Most containers today are of the 40 foot variety and thus are 2 TEU.
It is an important element of the logistics revolution that changed freight handling in the 20th century. Malcolm McLean invented the shipping container in the 1930s in New Jersey, and later founded Sea-Land corporation.
It is said that while sitting at a dock waiting for cargo he trucked in to be reloaded onto a ship, McLean realized that rather than loading and unloading the truck, the truck itself, with some minor modifications, could be the container that is transported.
Containerization revolutionized cargo shipping. Today, approximately 90% of cargo moves by containers stacked on transport ships. Over 200 million containers per year are now moved between those ports.