International travelers wishing to travel to the United States must first obtain an electronic entry permit. This requirement is applicable to all tourists whose countries are within the so-called Visa Waiver Program . In general, it includes all members of the European Union, Australia, South Korea and a few more.
This electronic authorization (ESTA) is similar to the form that is filled out on board the flight before arrival. The granting of authorization online is practically instantaneous, although depending on the requests in some cases it can take up to 72 hours or finally be denied.
The first step is to enter the ESTA (Electronic System of Travel Authorization) page (see link below), we must choose the language in which we want to complete the form and they will graphically indicate the steps to follow to request travel authorization. Remember that you must enter the personal data of each traveler , so if you travel with more people, all of them must do this process. Once filled in, the system generates an application number that you must sign up for follow-up. Once we see the OK of our authorization, they recommend us to bring a paper copy and the application number in case they ask for it when they arrive.
Official link | Apply for a visa (online mode)