Visa Waiver is a program that allows people from certain countries to travel to the United States without having to first obtain a stamp or visa in their passport. Under this program, people from the qualified countries can travel to the United States either to conduct business or as tourists. These visitors can remain in the United States for up to 90 days. However, visitors under this program cannot change their status or extend the length of time they can remain in the U.S. In addition, they cannot apply for other immigration benefits. Furthermore, prior to traveling to the United States, these visitors must register with the Electronic System for Travel Authorization (ESTA).