If you are visiting the US, authorities require passengers who are not US citizens and eligible to travel under the Visa Waiver Program to apply for an Electronic System for Travel Authorization (ESTA) online before departure. In most cases, the application is handled immediately and you will receive an answer instantly online.
Your ESTA or visa must be approved before boarding your flight. Apply for ESTA
Note: When you travel to the US, you must provide information on your first night stay and extended personal details.