Generally, a citizen of a foreign country who wishes to enter the United States must first obtain a visa, either a nonimmigrant visa for a temporary stay, or an immigrant visa for permanent residence. Visitor visas are nonimmigrant visas for persons who want to enter the United States temporarily for business (visa category B-1), for tourism (visa category B-2), or for a combination of both purposes (B-1/B-2).
A visa allows a foreign citizen to travel to a U.S. port-of-entry (generally an airport) and request permission to enter the United States. A visa does not guarantee entry into the United States. The Department of Homeland Security (DHS), U.S. Customs and Border Protection (CBP) officials at the port-of-entry have authority to permit or deny admission to the United States. If you are allowed to enter the United States, the CBP official will provide an admission stamp or a paper Form I-94, Arrival/Departure Record. Learn more about admissions and entry requirements, restrictions about bringing food, agricultural products, and other restricted/prohibited goods.