The United States Citizenship and Immigration Services (USCIS) is a sub-agency of the U.S Department of Homeland Security (DHS) which assumed responsibility in 2003, and it was created to enhance the security and efficiency of the national immigration services through the Homeland Security Act of 2002 (Pub. L. No. 107-296, 116 Stat. 2135) which dismantled the previous Immigration and Naturalization Service (INS) and separated it into three components within the Department of Homeland Security, the other two formed agencies were the Immigration and Customs Enforcement (ICE) and the Customs and Borders Protection (CBP), that was formed to oversee immigration enforcement and border security.
It is a congressional requirement that the agency be self-funded from the fees received, unlike other federal agencies which funding is within the U.S overall budget.
USCIS is exclusively responsible for administering immigration applications and handling the related forms, such as naturalization applications, Temporary workers applications, adjustment of status applications (Green Card), and refugee and asylum applications.