Alien For the 1979 movie, see Alien (movie). For live organisms which are not from Earth, see Extraterrestrial life. Aliens are foreigners to their surroundings. The word is commonly used in law to denote non-citizens of the country of their whereabouts, and in fiction, conspiracy theory and new-age discourse to denote extraterrestrial beings. The term can be used in a broader manner to refer to any object or concept. As an adjective it can be used to describe something foreign or something so different as to be uncomprehensible or incompatible. The word alien came from the Latin possessive adjective alienus = "belonging to someone else". Biology In biology the adjective alien, as in alien species, means that the normal locale is somewhere else, that a species or specimen exceptionally has been established in the area in question. Words with similar meaning in biology include exotic, adventive, introduced, and naturalized. These terms contrast with terms as indigenous and endemic. Alien species can sometimes wreak havoc on their new ecosystem, since in many cases, the local predators do not hunt them and so they will have no natural enemy. In some cases, people deliberately also introduced the matching predator, with equally disastrous effects. Introducing of alien species must therefore be prevented as much as possible. This can be difficult. Many marine species travel thousands of kilometers in the ballast water of ocean vessels, which are emptied at the destination port, other lifeforms with their cargo. People also often buy tropical animals and then discover that it is difficult to keep them and release them into the wild. In recent years, tropical species have been moving to the north and south of their original habitat which is attributed to global warming. Fiction and conspiracies In popular fiction and conspiracy theories, alien is a term that is often used to refer to life forms, especially intelligent life forms, that are of extraterrestrial origin, i.e. not coming from the Earth. Prime examples of how aliens are viewed are found in the movies Alien, E.T. the Extra-Terrestrial, Signs, and Independence Day. A peculiarity of this usage is its ethnocentricity: when humans in fictional accounts accomplish interstellar travel and land on a planet elsewhere in the universe, the local inhabitants of these other planets are usually still referred to as "alien," even though they are the native life form and the humans are the intruders. In general they are seen as unfriendly life forms. This may be seen as a reversion to the classic meaning of "alien" as referring to "other," in contrast to "us" in the context of the writer's frame of reference. Law In law, an alien is a foreigner who is not a citizen of the land in which he lives. If they live there, as opposed to being just a visitor, they may be called a "resident alien". The term illegal alien describes foreign nationals who have entered the country illegally. See also: Foreigner, Immigration, Naturalization, Wiktionary definition of alien Computing Alien is a computer program that converts between different Linux package distribution file formats. It supports conversion between Linux Standard Base, RPM, deb, Stampede (.slp) and Slackware (tgz) packages. See also Aliens in fiction External link Alien package converter software Further reading John C. Baird. 1987. The Inner Limits of Outer Space: A Psychologist Critiques Our Efforts to Communicate With Extraterrestrial Beings. Hanover: University Press of New England. ISBN 0-87451-406-1 Donald Goldsmith. 1997. The Hunt for Life on Mars. New York: A Dutton Book. ISBN 0525943366 Michael T. Lemnick. 1998. Other Worlds: The Search for Life in the Universe. New York: A Touchstone Book. Cliff Pickover. 2003 The Science of Aliens New York: Basic Books. ISBN 0-465-07315-8 FAVORITE ARTICLES: History of the World    History of the United States    History of Europe    Ancient History    History    Military History    World War I    Bombing of Dresden    California    US Constitution    Frank Sinatra    Boston    Marbury v. Madison This article is licensed under the GNU Free Documentation License at http://www.gnu.org/copyleft/fdl.html You may copy and modify it as long as the entire work (including additions) remains under this license. You must provide a link to http://www.gnu.org/copyleft/fdl.html To view or edit this article at Wikipedia go to http://www.wikipedia.org/wiki/Alien