[Excerpt] Four major principles underlie current U.S. policy on permanent immigration: the reunification of families, the admission of immigrants with needed skills, the protection of refugees, and the diversity of admissions by country of origin. These principles are embodied in the Immigration and Nationality Act (INA). The INA specifies a complex set of numerical limits and preference categories that give priorities for permanent immigration reflecting these principles. Legal permanent residents (LPRs) refer to foreign nationals who live permanently in the United States.