In law, an alien is a person who is not a citizen or national of a given country, though definitions and terminology differ to some degree depending on the continent or region of the world. The term "alien" is synonymous to "foreign national".
Lexicology
The term "alien" is derived from the Latinalienus, meaning stranger, foreign, etym. "belonging else". Similar terms to "alien" in this context include foreigner and lander.
Categories
Different countries around the world use varying terms for aliens. The following are several types of aliens:
a legal alien is a foreign national who is permitted by law to be in the host country. This is a very broad category which includes permanent residents, temporary residents, and visa holders or foreign visitors.
* a resident alien is a person who has permission by the government to reside and work in the country.
* a nonresident alien is a foreign national who is visiting a country as a tourist.
an illegal alien is any foreign national inside a country where he or she has no legal right to be. It covers a foreign national who has entered the country through illegal. In some countries it also covers an alien who entered the country lawfully but subsequently fallen out of that legal status.
an enemy alien is a foreign national of a country that is at war with the host country.
Common law jurisdictions
An "alien" in English law denoted any person born outside of the monarch's dominions and who did not owe allegiance to the monarch. Aliens were not allowed to own land and were subject to different taxes to subjects. This idea was passed on in the Commonwealth to other common law jurisdictions.
In Canada, the term "alien" is not used in federal statues. Instead, the term "foreign national" serves as its equivalent and is found in legal documents. The Immigration and Refugee Protection Act defines "foreign national" as "a person who is not a Canadian citizen or a permanent resident, and includes a stateless person."
Under the Immigration and Nationality Act of the United States, "he term 'alien' means any person not a citizen or national of the United States." The usage of the term "alien" dates back to 1798, when it was used in the Alien and Sedition Acts. Although the INA provides no overarching explicit definition of the term "illegal alien", it is mentioned in a number of provisions under title 8. Several provisions even mention the term "unauthorized alien". According to PolitiFact, the term "illegal alien" occurs in federal law, but does so scarcely. PolitiFact opines that, "where the term does appear, it’s undefined or part of an introductory title or limited to apply to certain individuals convicted of felonies." Because the U.S. law says that a corporation is a person, the term alien is not limited to natural humans because what are colloquially called foreign corporations are technically called alien corporations. Because corporations are creations of local state law, a foreign corporation is an out-of-state corporation. There are a multitude of unique and highly complex U.S. domestic tax laws and regulations affecting the U.S. tax residency of foreign nationals, both nonresident aliens and resident aliens, in addition to income tax and social security tax treaties and Totalization Agreements. "Alienage," i.e., citizenship status, has been prohibited since 1989 in New York City from being considered for employment, under that town's Human Rights legislation.
In the Arab states of the Persian Gulf, many non-natives have lived in the region since birth or since independence. However, these Arab states of the Persian Gulf do not easily grant citizenship to the non-natives.
On Latvian passports, the mark nepilsoņi refers to non-citizens or former citizens of the Soviet Union who do not have voting rights for the parliament of Latvia but have rights and privileges under Latvian law and international bilateral treaties, such as the right to travel without visas to both the European Union and Russia, where latter is not possible for Latvian citizens.
