Qualifying foreign nationals planning to visit the United States under the Visa Waiver Program (VWP) must now register under the Electronic System for Travel Authorization (ESTA) before traveling to the United States without a visa. ESTA is designed to identify those individuals who may be a security or law enforcement risk. The application takes only a few minutes to complete and can be completed online. Once approved, the ESTA authorization is valid for two years and can be renewed as often as required. Individuals who qualify for the VWP but who will be traveling to another country and stopping in the United States en route must also register under ESTA since the termination of the “Transit without a Visa” program. The USCIS Questions and Answers on ESTA fact sheet, which contains a list of participating VWP countries, can be read here.