Right now, 42 countries are part of the Visa Waiver Program (VWP), which lets travelers visit the U.S. without a visa. Business visitors from these countries can request WB (Waiver-Business) status when they arrive, for stays of up to 90 days. These visits cannot be extended. Travelers coming mainly for tourism would request WT (Waiver-Tourism) status instead.
All VWP visitors must get travel authorization through the Electronic System for Travel Authorization (ESTA) before boarding a flight. When they arrive, they are screened at the U.S. port of entry and registered in the Department of Homeland Security’s system.
Visitors without ESTA approval, or those who want to stay longer than 90 days, need to apply for a B-1 or B-1/B-2 visa to enter the U.S.