ESTA stands for the Electronic System for Travel Authorization. ESTA is an online application system developed by the United States government to pre-screen visa waiver travelers before they are allowed to board an airplane or ship that is bound for the United States. ESTA and a US Visa are not the same. ESTA is only a U.S.-entry requirement for passport holders from visa waiver countries (including Ireland).
The ESTA online application form takes between 5 and 10 minutes to complete. Upon the submission of your application, you will most likely know within seconds whether you are pre-approved to travel or not. Anyone who is denied via ESTA, must apply for a United States visitor visa (B-1 Business or a B-2 Tourist visa).
Any Irish passport holder who wants to enter or transit through the United States (by air or sea) under the Visa Waiver Program is required to apply for ESTA. It is not possible to apply for ESTA as a family. Each traveler including babies and infants must have his or her own approved ESTA Application before being allowed to board any U.S.-bound flight.
The Visa Waiver Program is a U.S. government program that enables citizens and nationals from 38 countries (including Ireland) to enter the United States for business or visitor purposes for up to 90 days without obtaining a visa. The advantage of entering the United States under the Visa Waiver Program is that you can travel to the United States on a short notice without first waiting to obtain a visa. A visa application process can take weeks or months to complete, while the ESTA application process can be completed online the same day.
The following countries are currently a part of the Visa Waiver Program: Andorra, Australia, Austria, Belgium, Brunei, Chile, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Monaco, Netherlands, New Zealand, Norway, Portugal, San Marino, Singapore, Slovakia, Slovenia, South Korea, Spain, Sweden, Switzerland, Taiwan, and the United Kingdom.
A travel authorization is normally valid for 2 years (unless your passport expires earlier).
You can apply for your travel authorization at any time and do not need to have your itinerary arranged in advance.