Normally, foreign nationals need a visa (except for those who qualify for visa-free travel with ESTA under the Visa Waiver Program) in order to enter into the United States. There is a special type of visa for those on business trips and vacations: the B-1/B-2 (business/tourist) visa.
IMPORTANT: All visa options listed here are nonimmigrant visas. These visas are only valid for temporary stays in the United States. If you want to live and/or work permanently in the United States, then you need to apply for an immigrant visa (Green Card).
The visitor visa grants entry for up to 180 days (per stay) for limited business purposes.
The visitor visa grants entry for up to 180 days (per stay) for purely tourism-related purposes.