An alien is a foreign-born individual in the U.S. who is not an American citizen. A legal alien has an immigrant or nonimmigrant visa. Immigrant visas are issued to foreign-born individuals who intend to live permanently in the U.S.; nonimmigrant visas are for foreign-born individuals wishing to enter the U.S. on a temporary basis.
An illegal alien or undocumented immigrant does not have a valid visa or other immigration documentation either because he entered the U.S. illegally, stayed longer than his temporary visa permitted, or otherwise violated the terms under which he was admitted.
An undocumented alien/immigrant is a foreign-born person who does not have a legal right to be in America. Some undocumented aliens sneak into the U.S. without being legally admitted and inspected by U.S. immigration authorities; many others originally come to the country legally, as tourists or on other nonimmigrant (temporary) visas such as to conduct business, obtain medical treatment, or attend school—then they fail to leave when their visas expire or don’t adhere to the rules of their visa: people are restricted to the activity or reason for which they were allowed entry. For example, an individual with a student visa must continue to be enrolled in school throughout the period of the visa.
Regardless of how long an undocumented alien/immigrant has been in the U.S., most do not have a route to achieving legal status; even those who pay taxes, work hard, and contribute to their communities.
When undocumented aliens/immigrants have qualifying relatives or employers who can provide a pathway to a visa, many are still unable to take advantage of that process for years due to extremely long backlogs. In addition to that challenge, even if there is a visa available, numerous undocumented immigrants who entered the U.S. illegally are generally barred from obtaining legal status while they’re inside the U.S; they cannot “adjust status” and get a green card without first leaving the country.
Leaving the U.S. to obtain a visa can have significant negative consequences. A person who has been out of status for more than 180 days, but less than one year, is barred from being
re-admitted or re-entering the U.S. for three years; while someone who has been out of status for more than one year is barred for 10 years. Although waivers to these bars exist, they are difficult to obtain.
In terms of humanitarian protection—most people fleeing danger cannot access that protection. Each year, the U.S. sets a numerical limit on how many refugees will be admitted for humanitarian reasons. And to be admitted as refugees, individuals must be able to demonstrate a “well-founded fear of persecution based on race, religion, membership in a particular social group, political opinion, or national origin.” Asylum seekers are people already in the U.S. who fear returning to their home countries—they must prove they meet the definition of a refugee.
