What is ESTA (Electronic System for Travel Authorization)?

The Electronic System for Travel Authorization (ESTA) is an automated system, used to determine the eligibility of visitors to travel to the U.S. under the Visa Waiver Program and examine whether such travel will pose any law enforcement or security risk. Starting on January 12, 2009, if any person visiting the United States under the visa waiver program is mandatory to hold an approved ESTA Travel Authorization.