To learn everything about the U.S. Visa process, information can be found on the U.S. Department of State’s website.
Before traveling to the U.S., a citizen of a foreign country must generally obtain a nonimmigrant visa for temporary stay or an immigrant visa for permanent residence. The type of visa you will need is based on the purpose of your travel.
United States citizens don’t need a U.S. visa for travel, but when planning travel abroad may need a visa issued by the embassy of the country they wish to visit.
Continue reading and for more information visit http://travel.state.gov/visa/visa_1750.html