From the Document: "The Department of Defense (DOD) relies on a wide-ranging and complex industrial base for the products and services that enable the Department's warfighting capabilities. Definitions of what this industrial base encompasses vary in scope and emphasis. Some analysts and experts distinguish between a domestic 'defense industrial base' (DIB) and a global DIB. The domestic DIB includes public-sector (government-owned, government-operated) facilities and private-sector (commercial) companies located in the United States. Congress has taken some interest and action to support and sustain the domestic DIB. [...] The commercial companies that contract with DOD are diverse, ranging in size from small businesses to some of the world's largest corporate enterprises. These commercial companies provide a wide variety of products to DOD, encompassing everything from complex military-unique platforms (such as aircraft carriers) to common items sold commercially (such as laptop computers, clothing, and food). These companies also provide a wide variety of services, including everything from routine services (e.g., information technology (IT) support) to highly specialized services (e.g., launching space vehicles)."
CRS In Focus, IF10548
Congressional Research Service: https://crsreports.congress.gov/