Immigration laws, regulated by the U.S. Citizenship and Immigration Services (USCIS), cover the orderly immigration or visitation of foreign nationals into the United States. An immigrant is a person who wants to enter, live, and work in the U.S. indefinitely; whereas, temporary visitors are just that, temporary visitors. They wish to enter for a particular purpose, even stay for a period of years, but not stay indefinitely. Immigration is a highly complex area of law and may include such areas as; entrance eligibility, reunification with family, work/study, or refuge/asylum.