U.S. Citizenship and Immigration Services: Authorities and Procedures [Updated June 1, 2022] [open pdf - 755KB]
From the Document: "Congress has specified the conditions [hyperlink] under which non-U.S. nationals ('aliens' [hyperlink], as the term is used in the Immigration and Nationality Act [INA]) may lawfully enter or remain in the United States. Under this framework, aliens who satisfy applicable requirements may qualify for certain types of immigration benefits, such as adjustment to lawful permanent resident [hyperlink] (LPR) status. U.S. Citizenship and Immigration Services [hyperlink] (USCIS), a component of the Department of Homeland Security (DHS), is tasked with adjudicating immigration benefit applications. This Legal Sidebar provides a brief overview of USCIS's authorities and procedures."
CRS Legal Sidebar, LSB10671
Congressional Research Service: https://crsreports.congress.gov/