In U.S. law, an alien is a person who owes political allegiance to another country or government and not a native or naturalized citizen of the land where they are found.[1] Types of "alien" persons are:
An alien who is legally permitted to remain in a country (which is foreign to him/her) on specified terms may be called a legal alien of that country.
An alien who has temporary or permanent residence in a country (which is foreign to him/her) may be called a resident alien of that country.
A visitor with the legal right to visit a country (which is foreign to him/her) may be called a nonresident alien of that country.
The term illegal alien describes a foreign national who resides in another country unlawfully, either by entering that country at a place other than a designated port-of-entry or as result of the expiration of a non-immigrant visa. See illegal immigration for greater detail.