All nationals and citizens of Visa Waiver Program (VWP) countries will be required by law to obtain a travel authorization prior to initiating travel to the United States under the VWP. This authorization may be obtained online through the Electronic System for Travel Authorization (ESTA™), a free Internet application administered by the Department of Homeland Security (DHS) through a U.S. Government Web site. at http://cbp.gov/xp/cgov/travel/id_visa/esta/