International trading flourishes these years, shipping as an important part of trading played an important role in world economy. A shipping container is a container with strength suitable to withstand shipment, storage, and handling. Shipping containers and plastic seals range from large reusable steel boxes used for intermodal shipments to the ubiquitous corrugated boxes. In the context of international shipping trade, "container" or "shipping container" is virtually synonymous with “intermodal freight container".

Freight containers are a reusable transport and storage unit for moving products and raw materials between locations or countries. There are approximately seventeen million intermodal containers in the world; a large proportion of the world's long-distance freight generated by international trade is transported in shipping containers and plastic seals. Corrugated boxes are commonly used as shipping containers. They are made of corrugated fiberboard which is light weight, recyclable, and strong enough to ship a variety of products. Customized cushioning, blocking and bracing, carrying handles, lift rings; locks, etc. are common to facilitate handling and to protect the contents. Often, these shipping containers are reusable.

Aircraft loads can consist of containers, pallets, or a mix of ULD types, depending on requirements. The table below indicates the maximum capacity of an aircraft for all-container and all-pallet configurations. In some aircraft the two types must be mixed as some compartments take only specific ULDs. It allows a large quantity of cargo with plastic seals to be bundled into a single unit. Since this leads to fewer units to load, it saves ground crews time and effort and helps prevent delayed flights. Each ULD has its own packing list, manifest, or tracking identification to improve control and tracking of contents. Custom containers are used for shipments of products such as weapons and aviation components. Specialized shipping containers include: High Cube Containers, pallet wide, open tops, side loaders and temperature controlled containers.