An approved ESTA (Electronic System for Travel Authorization) is generally valid for two years from the date of authorization, allowing multiple visits to the United States within that period without needing to reapply. However, if your passport expires before the two years, the ESTA validity will end on the passport's expiration date. Each visit under ESTA can last up to 90 days for tourism or business purposes, but the total stay cannot be extended beyond that under the Visa Waiver Program