1、Congressional Research Service The Library of CongressCRS Report for CongressReceived through the CRS Web98-918 EPWUpdated September 15, 1999Immigration FundamentalsJoyce VialetSpecialist in Immigration PolicyDomestic Social Policy DivisionKey Definitions. Immigration to the United States is regulat
2、ed by Federal law. Thebasic U.S. law, the Immigration and Nationality Act (INA), was enacted in 1952 andsignificantly amended since, most recently by the Illegal Immigration Reform andImmigrant Responsibility Act of 1996. The INA defines an alien as “any person not acitizen or national of the United
3、 States,” and sets forth the conditions under which aliensmay enter the United States. The term alien is synonymous with noncitizen. It includesaliens who are here legally, as well as aliens who are here illegally, in violation of the INA. The two basic types of legal aliens are immigrants and nonim
4、migrants. Immigrantsare persons admitted as permanent residents of the United States. Nonimmigrants areadmitted temporarily as visitors for a specific purpose for example, as tourists, foreignstudents, diplomats, temporary agricultural workers, exchange visitors, or intracompanybusiness personnel. T
