From the Summary: "The parole provision in the Immigration and Nationality Act (INA) gives the Secretary of the Department of Homeland Security (DHS) discretionary authority to 'parole into the United States temporarily under such conditions as he may prescribe only on a case-by-case basis for urgent humanitarian reasons or significant public benefit any alien applying for admission to the United States.' Immigration parole is official permission to enter and remain temporarily in the United States. It does not constitute formal admission under the U.S. immigration system. An individual granted parole (a parolee) is still considered an applicant for admission. A parolee is permitted to remain in the United States for the duration of the grant of parole, and may be granted work authorization. The DHS Secretary's parole authority has been delegated to three agencies within the department: U.S. Citizenship and Immigration Services (USCIS), U.S. Immigration and Customs Enforcement (ICE), and U.S. Customs and Border Protection (CBP). Parole can be requested by foreign nationals inside or outside the United States in a range of circumstances. Major parole categories include port-of-entry parole, advance parole, humanitarian parole, and parole-in-place."
CRS Report for Congress, R46570
Congressional Research Service: https://crsreports.congress.gov/