Nonimmigrant visas are for foreign nationals coming to the U.S. temporarily. International travelers come to the U.S. for a wide variety of reasons, including tourism, studying, business, medical treatment and certain types of temporary work. The type of visa needed is defined by immigration law, and relates to the principal purpose of your travel.
U.S. immigration law presumes that every visitor visa applicant is an intending immigrant and applicants for visitor visas must overcome this presumption. Therefore, even though some visas are considered ‘dual intent’, meaning that you may attempt to obtain permanent residency while under temporary visa classification, most nonimmigrant visas, however, require you establish the demonstration of nonimmigrant intent. This means you should demonstrate that you have a permanent residence in your home country that you have no intention of abandoning. The duration of time you may spend in the U.S. can range from a few days to several years, depending on the visa. In most situations, your spouse and unmarried children under the age of 21 may accompany you on a derivative visa.