US ESTA (Electronic System for Travel Authorization) is the pre-travel approval that citizens of the 41 Visa Waiver Program (VWP) countries must obtain before short visits to the United States Fact. Introduced in 2008, ESTA became the model for electronic travel authorizations worldwide Fact.
Fee and validity
The government fee is US$40.27 ($4.00 application + $36.27 authorization). Once approved, ESTA is valid for two years and multiple entries, with stays of up to 90 days Fact.
Approval is not entry
ESTA approval is boarding eligibility, not a guarantee of entry. The final decision is made by a CBP officer at the US port of entry, which is why an accurate application matters Fact.