CBP is the short name for U.S. Customs and Border Protection, the American government service that watches the country’s borders. When you fly into the United States, the officers who check your passport and ask what you are bringing in usually work for CBP. They also work at seaports and along the land borders with Mexico and Canada. Their job is to decide who may enter, and to stop goods that should not come in — drugs, undeclared money, some foods and plants. People often just say “customs” for the airport desk, and that is fair enough in everyday talk, though actually CBP is bigger than that old customs office: it also includes the Border Patrol, who watch the land between official crossing points. It is a US name only; other countries have their own border services and do not call them CBP. You will see the letters on uniforms, forms, and signs at US airports. It is official language, not casual chat.