From the Background: "Foreign assistance is an instrument of U.S. policy through which the U.S. government provides resources to another country's government, civil society, or other private sector entity on a grant or concessional loan basis. Most U.S. foreign assistance is administered by the U.S. Agency for International Development (USAID); the Millennium Challenge Corporation (MCC); the U.S. Departments of State, Agriculture (USDA), the Treasury, and Defense (DOD); or is channeled through multilateral organizations."
CRS In Focus, IF10183
Congressional Research Service: https://crsreports.congress.gov/