Customs is an authority or agency in a country responsible for collecting tariffs and for controlling the flow of goods, including animals, transports, personal effects, and hazardous items, into and out of a country. Traditionally, customs has been considered as the fiscal subject that charges customs duties and other taxes on import and export. In recent decades, the views on the functions of customs have considerably expanded and now covers three basic issues: taxation, security, and trade facilitation.

An importer is the receiving country in an export from the sending country. Importation and exportation are the defining financial transactions of international trade. Import is part of the International Trade which involves buying and receiving of goods or services produced in another country. The seller of such goods and services is called an exporter, while the foreign buyer is known as an importer.