Travelers to the U.S. need a valid passport and either an ESTA or a visa to enter. Most visitors can stay for up to 90 days with an approved ESTA under the Visa Waiver Program, which should be applied for at least 72 hours before departure. If you are not eligible, you will need a B-1/B-2 visitor visa.
At entry, U.S. Customs and Border Protection may ask about your trip, so be ready to show proof of onward travel, accommodation, and funds. For the most accurate and up-to-date information, visit the official U.S. government website.