ESTA stands for the Electronic System for Travel Authorization, sometimes also referred to as an ESTA visa. The USA ESTA application is an automated system implemented by the United States government and managed by the Department of Homeland Security. It establishes the eligibility of citizens or nationals of designated countries to travel to the United States before they begin their journey. Thanks to the ESTA visa application, US government conducts an initial screening of all passengers before they are granted the right to enter the United States. Everybody traveling to the United States with a passport from a visa waiver country must fill out the ESTA form online, instead of the previously required paper entry forms.
As a measure of increased security, applying for an USA ESTA visa became obligatory on 12 January 2009. Business and tourist travelers going to the United State as nationals of Visa Waiver Programme (VWP) countries must apply online and be granted an ESTA before the start of their journey. For more, visit USA ESTA.