If you want to travel to the United States, you’ve probably heard of ESTA. If you live in a visa waiver country, you’ve almost certainly heard of it, as it is the method used to get your visa waiver. But if you haven’t heard of it, read this article for a quick crash course.

ESTA stands for Electronic System for Travel Authorization. It’s a short online application that you fill out and submit to the Department of Homeland Security. Once you submit it, they analyze your application and determine whether you are eligible for a visa waiver.

Anyone traveling to the United States from a visa waiver country will require either a visa or a visa waiver obtained through an ESTA application. This includes non-ticketed infants and other minor children.

If you submit your visa waiver application and are denied, that doesn’t mean you definitely can’t travel. It just means you’ll need to submit an application for a full visa so the Department of Homeland Security can more fully analyze your background before admitting you to the United States.

Only those people with citizenship and passports (or approved national resident status) from visa waiver countries can apply for a visa waiver through ESTA. You can find out if you qualify by going to the Department of Homeland Security’s website on visa waivers.

There are a few other requirements to apply for a visa waiver. You can’t currently be in possession of a visitor’s visa, for example, and your travel plans have to be shorter than 90 days. It has to be for business, pleasure, or transit – you can’t use a visa waiver to come to the USA for school, for example.

It’s not that hard to submit a visa waiver application through ESTA. The application itself should only take about 20 minutes. Then it’s just a matter of waiting for a decision.