INS stands for Immigration and Naturalization Service, a U.S. federal agency that was abolished on March 1, 2003, according to the official website of the Department of Homeland Security. The INS was formerly part of the Department of Justice and dealt with all legal and illegal immigration.
In 2003, the functions of the INS were transferred to three different agencies under the newly created Department of Homeland Security: U.S. Citizenship and Immigration Services, Immigration and Customs Enforcement, and Customs and Border Patrol, according to the official website of the Department of Homeland Security. The restructuring was part of the government's response to the September 11 attacks in 2001.