Visa Waiver Program (VWP) Definition

The VWP allows nationals from certain countries to come to the United States without a visa, so long as they're planning on being tourists, and to leave within 90 days. They are not (except in rare cases) permitted to extend their stay or change their immigration status. For example, someone who enters on the visa waiver program cannot then ask to stay on in the U.S. as a student in F-1 status, but would have to leave the U.S. and apply for a student visa at a U.S. consulate abroad.