Refrigerated containers are like ordinary portable storage containers in the way that they transport goods across long distances. The difference is that a refrigerated container, or reefer, has refrigeration equipment installed inside of it. This enables the regulation of low temperatures inside the container, and therefore allows the container to store temperature sensitive cargo.
The challenge of moving perishable cargo such as food has often been limited by how long travel takes and how long the cargo can be preserved. While there are methods to help extend the life of items like food, such as adding salts on it to help keep it fresh, methods like that will not work for all goods. Some other cargo can only exist under very specific conditions. The transport of frozen goods, of temperature-sensitive chemicals, is impossible without constant temperatures that cannot be achieved merely by transporting it with ice in an insulated container.
Refrigeration remains one of the most successful means of keeping goods under cold temperatures, and refrigerated containers let transporters do just that. These units are portable storage containers with the difference of having a small refrigeration unit on one side of the container. The refrigeration units may be ran by their own generators, which provide the power that they need to keep a constant temperature. They can also be made to function using external power, and thus saving costs by making them lighter, albeit more reliant on power from the carrying vehicles such as ships or trucks.
Developments towards the technology of refrigerated containers include the use of refrigeration units that can deal with containers as large as 20 or even 40 feet in length, while 8.5 feet in height and 8 feet in width. These larger containers will be able to transport a greater load of goods to where they are needed.