A visa to the United States allows someone to come to a U.S. port-of-entry and apply for entry to the U.S. Visas are necessary for many people from other countries to come to the U.S. to visit or work.
Visas typically come in the form of a small slip of paper or a stamp in one’s passport. Visitors may be asked to present their visa to the authorities at the border when entering the U.S., such as Customs and Border Protection (CBP).
Visas do not necessarily guarantee entry into the United States, but instead allow a person to enter a port-of-entry whether by land, sea or air.
Some visitors may not need a visa for some short visits. Residents of countries that participate in the Visa Waiver Program (VWP) may be able to enter a port-of-entry with only their passport.