The ESTA, or Electronic System for Travel Authorization, is a document that allows you to travel to the United States visa-free. ESTA applications can be completed online in minutes prior to your arrival at a U.S. port of entry. The ESTA program is entirely digital. You can complete and submit the application online. Then, the ESTA will appear when you scan your e-passport at a port of entry. Most developed nations today have e-passports, and the ESTA program covers most of the developed world.