Alien (law) in the context of Naturalized citizen

The Iberian Union or the Hispanic Monarchy, describes the period from 1580 to 1640 in which the Monarchy of Spain under the Habsburg dynasty, then the personal union of the crowns of Castile and Aragon, brought in personal union also the Kingdom of Portugal. It incorporated the entire Iberian Peninsula except Andorra, as well as Portuguese and Spanish overseas possessions, under the Spanish Habsburg monarchs Philip II, Philip III, and Philip IV. The union began after the Portuguese succession crisis of 1580 and the ensuing War of the Portuguese Succession, and lasted until the Portuguese Restoration War, during which the House of Braganza was established as Portugal's new ruling dynasty with the acclamation of John IV as the new king of Portugal.

As a personal union, the Kingdom of Portugal, the Crown of Castile and the states of the Crown of Aragon remained independent states, sharing only a single monarch. The kings from the Spanish branch of the House of Habsburg were the only element that connected the multiple kingdoms and territories, ruled by the six separate government councils of Castile, Aragon, Portugal, Italy, Flanders-Burgundy, and the Indies. For periods, Portugal maintained a viceroy, appointed by the king, although the turnover was often rapid; in the 60 years of the Union, the country had 13 viceroys and four regency councils (see List of viceroys of Portugal). Similar viceroys were appointed in Aragon, Catalonia, Valencia and other kingdoms of the Union. The governments, institutions, and legal traditions of each kingdom remained independent of one another. Alien laws (Leyes de extranjería) determined that a national of one kingdom was a foreigner in all other kingdoms.

National treatment is a principle in international law. Utilized in many treaty regimes involving trade and intellectual property, it requires equal treatment of foreigners and locals. Under national treatment, a state that grants particular rights, benefits or privileges to its own citizens must also grant those advantages to the citizens of other states while they are in that country. In the context of international agreements, a state must provide equal treatment to citizens of the other states participating in the agreement. Imported and locally produced goods should be treated equally — at least after the foreign goods have entered the market.

While this is generally viewed as a desirable principle, in custom it conversely means that a state can deprive foreigners of anything of which it deprives its own citizens. An opposing principle calls for an international minimum standard of justice (a sort of basic due process) that would provide a base floor for the protection of rights and of access to judicial process. The conflict between national treatment and minimum standards has mainly played out between industrialized and developing nations, in the context of expropriations. Many developing nations, having the power to take control over the property of their own citizens, wished to exercise it over the property of aliens as well.

Naturalization (or naturalisation) is the legal act or process by which a non-national of a country acquires the nationality of that country after birth. The definition of naturalization by the International Organization for Migration of the United Nations excludes citizenship that is automatically acquired (e.g. at birth) or is acquired by declaration. Naturalization usually involves an application or a motion and approval by legal authorities. The rules of naturalization vary from country to country but typically include a promise to obey and uphold that country's laws and taking and subscribing to an oath of allegiance, and may specify other requirements such as a minimum legal residency and adequate knowledge of the national dominant language or culture. To counter multiple citizenship, some countries require that applicants for naturalization renounce any other citizenship that they currently hold, but whether this renunciation actually causes loss of original citizenship, as seen by the host country and by the original country, will depend on the laws of the countries involved. Naturalization is politicized due to the reshaping of the electorate of the country.

A travel visa (from Latin charta visa 'paper that has been seen'; also known as visa stamp) is a conditional authorization granted by a polity to a foreigner that allows them to enter, remain within, or leave its territory. Visas typically include limits on the duration of the foreigner's stay, areas within the country they may enter, the dates they may enter, the number of permitted visits, or if the individual can work in the country in question. Visas are associated with the request for permission to enter a territory and thus are, in most countries, distinct from actual formal permission for an alien to enter and remain in the country. In each instance, a visa is subject to border control at the time of actual entry and can be revoked at any time. Visa evidence most commonly takes the form of a sticker endorsed in the applicant's passport or other travel document but may also exist electronically. Some countries no longer issue physical visa evidence, instead recording details only in border security databases.

Some countries require that their citizens, and sometimes foreign travelers, obtain an exit visa in order to be allowed to leave the country.

Illegal immigration, or unauthorized immigration, occurs when foreign nationals, known as aliens, violate US immigration laws by entering the United States unlawfully, or by lawfully entering but then remaining after the expiration of their visas, parole or temporary protected status.

Between 2007 and 2018, visa overstays have accounted for a larger share of the growth in the illegal immigrant population than illegal border crossings, which have declined considerably from 2000 to 2018. In 2022, 37% of unauthorized immigrants were from Mexico, the smallest share on record. El Salvador, India, Guatemala and Honduras were the next four largest countries. As of 2016, approximately two-thirds of unauthorised adult immigrants had lived in the US for at least a decade. As of 2022, unauthorized immigrants made up 3.3% of the US population, though nearly one-third of those immigrants have temporary permission to be in the United States, such as those in Deferred Action for Childhood Arrivals. According to an August 2025 Pew Research Center report, the unauthorized immigrant population grew by 3.5 million between 2021 and 2023, reaching a record 14 million. July 2024 data for border crossings showed the lowest level of border crossing since September 2020.

A foreign portfolio investment is a grouping of assets such as stocks, bonds, and cash equivalents. Portfolio investments are held directly by an investor or managed by financial professionals. In economics, foreign portfolio investment is the entry of funds into a country where foreigners deposit money in a country's bank or make purchases in the country's stock and bond markets, sometimes for speculation.

Denization is an obsolete or defunct process in England and Ireland and the later Kingdom of Great Britain, the United Kingdom, and the British Empire, dating back to the 13th century, by which an alien (foreigner), through letters patent, became a denizen, thereby obtaining certain rights otherwise normally enjoyed only by the King's (or Queen's) subjects, including the right to hold land. The denizen was neither a subject (with citizenship or nationality) nor an alien, but had a status akin to permanent residency today. While one could become a subject via naturalisation, this required a private act of Parliament (or latterly of a colonial legislature); in contrast, denization was cheaper, quicker, and simpler. Denization fell into obsolescence when the British Nationality and Status of Aliens Act 1914 (4 & 5 Geo. 5. c. 17) simplified the naturalisation process.

Denization occurred by a grant of letters patent, an exercise of the royal prerogative. Denizens paid a fee and took an oath of allegiance to the crown. For example, when Venetian mariner Gabriel Corbet was granted letters of denization in 1431 for service upon the seas to Henry V and Henry VI, he was required to pay 40 shillings into the hanaper for the privilege.

A certificate of identity, sometimes called an alien's passport, is a travel document issued by a country to non-citizens (also called aliens) residing within their borders who are stateless persons or otherwise unable to obtain a passport from their state of nationality (generally refugees). Some states also issue certificates of identity to their own citizens as a form of emergency passport or otherwise in lieu of a passport. The visa requirements of certificates of identity may be different from those of regular passports.

Ger toshav (Hebrew: גר תושב, ger: "foreigner" or "alien" + toshav: "resident", lit. "resident alien") is a halakhic term used in Judaism to designate the legal status of a Gentile (non-Jew) living in the Land of Israel who does not want to convert to Judaism but agrees to observe the Seven Laws of Noah, a set of imperatives which, according to the Talmud, were given by God as a binding set of universal moral laws for the "sons of Noah"—that is, all of humanity. A ger toshav, especially one who decides to follow the Noahic covenant out of religious belief rather than ethical reasoning, is commonly deemed a "Righteous Gentile" (Hebrew: חסיד אומות העולם, Chassid Umot ha-Olam: "Pious People of the World"), and is assured of a place in the World to Come (Olam Ha-Ba).

Koreans in China include both ethnic Koreans with Chinese citizenship and foreign residents living in China such as South Koreans (Chinese: 在华韩国人·韩裔), North Koreans (Chinese: 在华朝鲜人·朝鲜裔) and other Overseas Koreans. For this reason, ethnic Koreans with Chinese citizenship are termed Korean Chinese, Joseonjok, Chosŏnjok (Korean: 조선족; Hancha: 朝鮮族), and their official name in China is Chaoxianzu (朝鲜族; Cháoxiǎnzú; 'Joseon ethnic group'). Korean Chinese are the 13th largest ethnic minority group in China. They form a diasporic community with cultural ties to the Korean Peninsula across generations, including among individuals who have never visited Korea.

Most native Korean Chinese live in the Northeast China. Significant populations can also be found in Heilongjiang and Inner Mongolia, with a sizable expatriate community in Shanghai and Shandong across the Yellow Sea. According to the South Korean government, the combined population of Koreans with Chinese nationality, South Korean and North Korean expats in China is 2,109,727 in 2023.

Nationality law is the law of a sovereign state, and of each of its jurisdictions, that defines the legal manner in which a national identity is acquired and how it may be lost. In international law, the legal means to acquire nationality and formal membership in a nation are separated from the relationship between a national and the nation, known as citizenship. Some nations domestically use the terms interchangeably, though by the 20th century, nationality had commonly come to mean the status of belonging to a particular nation with no regard to the type of governance which established a relationship between the nation and its people. In law, nationality describes the relationship of a national to the state under international law and citizenship describes the relationship of a citizen within the state under domestic statutes. Different regulatory agencies monitor legal compliance for nationality and citizenship. A person in a country of which he or she is not a national is generally regarded by that country as a foreigner or alien. When the sovereignty over a territory is transferred from one state to another, individuals may be given the right of option of nationality. A person who has no recognised nationality to any jurisdiction is regarded as stateless.

Illegal immigration, or unauthorized immigration, occurs when foreign nationals, known as aliens or non-citizens, violate US immigration laws by entering the United States unlawfully, or by lawfully entering but then remaining after the expiration of their visas, parole or temporary protected status.

Between 2007 and 2018, visa overstays have accounted for a larger share of the growth in the illegal immigrant population than illegal border crossings, which have declined considerably from 2000 to 2018. In 2022, 37% of unauthorized immigrants were from Mexico, the smallest share on record. El Salvador, India, Guatemala and Honduras were the next four largest countries. As of 2016, approximately two-thirds of unauthorised adult immigrants had lived in the US for at least a decade. As of 2022, unauthorized immigrants made up 3.3% of the US population, though nearly one-third of those immigrants have temporary permission to be in the United States, such as those in Deferred Action for Childhood Arrivals. According to an August 2025 Pew Research Center report, the unauthorized immigrant population grew by 3.5 million between 2021 and 2023, reaching a record 14 million. July 2024 data for border crossings showed the lowest level of border crossing since September 2020.

Aliens entering the United States must obtain a visa from one of the U.S. diplomatic missions. Visitors may be exempt if they are citizens of one of the visa-exempt or Visa Waiver Program countries.

The same rules apply for travel to all U.S. states, Washington, D.C., Puerto Rico and the U.S. Virgin Islands, as well as to Guam and the Northern Mariana Islands with additional waivers, while similar but separate rules apply to American Samoa.

This is a list of militaries that recruit foreign applicants. This includes any individuals who are aliens of the polity whose armed forces they are being recruited to join by professional recruiters. The foreigners do not need to be legal residents of that nation, but may gain legal residence status by joining the armed forces. More than 90 states have implemented such recruitment policies between 1815 and 2020.

In customary international law, an enemy alien is any alien native, citizen, denizen or subject of any foreign nation or government with which a domestic nation or government is in conflict and who is liable to be apprehended, restrained, secured and removed. Usually, the countries are in a state of declared war.