A nonimmigrant visa, is a temporary visa, given under a specific qualifying category as defined by immigration laws and regulations, that allows an alien to enter the United States for a temporary period such as, but not limited to, a person for business, tourism, employment, investment, studies, and other acceptable purposes. A nonimmigrant visa is usually issued to an alien at an American embassy or consulate. Under appropriate circumstances, an alien already in the United States, in a nonimmigrant category may seek a change of status to another nonimmigrant visa category.

An immigrant visa (permanent resident status) is a visa that gives an alien the right to work and live in the United States as long as he or she wishes, in effect permanently. An immigrant visa is issued by the consular office at an American embassy or consulate upon an approved case. If an alien is in the United States, he or she maybe eligible for adjustment of status to lawful permanent resident.

A refugee is an alien who has been granted admission to the United States following an official determination that (s)he is unable or unwilling to return to the home country because of actual or well-founded fear of persecution on account of race, religion, nationality, and membership in a particular group or political opinion.

An asylee is an alien who was granted political asylum after entering the United States following an official determination that (s)he is unable or unwilling  to return to the home country because of actual or well-founded fear of persecution on account of race, religion, nationality, and membership in a particular group or political opinion.