About the U.S. Visa Waiver Program and ESTA
The Electronic System for Travel Authorization (ESTA) is a system under the U.S. Visa Waiver Program (VWP).
If you are a citizen (or an eligible national) of one the 40 approved countries that are part of the WVP, and are planning to visit the U.S. for 90 days or less, you may be able to enter the U.S. using an ESTA instead of an entry visa.
ESTA is only available to travelers entering the U.S. for Business or Tourism purposes, who do not already possess a visitor visa. Keep in mind that, while traveling on an ESTA, you are not allowed to study or work in the U.S.
This authorization remains valid for 2 years after you receive it, but you may not stay in the U.S. for more than 90 days in a row or for more than 180 days within a 365-day period.
ESTA applications are processed much faster than regular Visa applications, as they bypass the consular process entirely. However you should reserve at least 72 hours before your planned date of departure for the processing of your ESTA request - although in some cases we may be able to get it processed in under 3 hours.
Nationals of the Visa Waiver Program countries who have had their ESTA denied or revoked are required to get a U.S. visa in order to travel to the U.S.