The USCIS handles any duties relating to immigration. The United States Citizenship and Immigration Services replaced INS. It is now a division in the United States Department of Homeland Security.
The main focus of the Bureau is to protect the US and to eliminate immigration back log. The acting director is Jonathan Scharfen. USCIS process visa and naturalization petitions as well as asylum and refugee applications.
It also grants permanent resident status and US citizenship. INS handled these duties before September 11. After the attacks George W. Bush signed the Homeland Security Act of 2002.
It gave the INS functions over to the Dept. of Homeland Security. The USCIS has every form you need in regards to immigration and naturalization.
They have the main forms as well as smaller forms such as change of address forms. All the forms are available online and need only to be mailed back along with the fee. Not all forms require a fee. Forms include employment authorization, and applications to stop deportation.