The following article is about the term alien as most commonly used. For the term applying to hypothesized other forms of life in the universe see: Extraterrestrial life
An alien is a person who is a member of another family, race, or nation than the people among whom he or she lives. In American legal terminology, anyone who is not an American citizen is classified as an alien.
An alien is a foreign-born person who has not qualified as a citizen of the country in which he or she lives.
In other countries, the term "foreigner" may be used instead of "alien". The word "alien" may also be used to describe creatures from other planets. Because such creatures have not yet been discovered, the term is usually confined to the realm of science fiction, although scientists and the media may use it when speculating about such life forms.