A more thorough explanation:

Definition: A courier is a person who delivers packages, parcels, and other items. In international law, a courier is a messenger authorized by a sending state to deliver a diplomatic pouch.

Examples:

• A courier delivered a package to my office this morning.
• The company uses couriers to deliver important documents to clients.
• The embassy sent a courier to deliver a diplomatic pouch to the consulate.

The examples illustrate how a courier is a person who is responsible for delivering items from one place to another. They can be used by individuals or companies to deliver packages or documents. In international law, a courier is authorized by a sending state to deliver a diplomatic pouch, which is a secure container used to transport sensitive diplomatic correspondence or materials.