Customs definition
Customs are the rules for moving goods across borders.
Customs refers to the rules and procedures of moving goods in and out of countries. A country’s customs organization facilitates international trade by ensuring its compliance with relevant laws and regulations and collecting tariffs.
Customs includes:
- Enforcing import and export laws
- Collecting duties and taxes
- Screening goods and travelers at ports of entry
- Seizing prohibited or dangerous items
- Verifying documentation of imports and exports
- Protecting a country’s economic, health and security interests at the border

What US agency is responsible for customs?
US Customs and Border Protection (CBP) has been responsible for customs since it was created in 2003. CBP combined four existing agencies: the US Customs Service, the Immigration and Naturalization Service, Border Patrol, and the Animal and Plant Health Inspection Service.
From 1789 to 2003, the US Customs Service oversaw international trade, under the purview of the Treasury Department. For the first 100 years of its existence, tariffs collected by the Customs Service were the main source of income for the US government.