From the Document: "Throughout its history, the Department of Defense (DOD) has relied on contractors to support a wide range of military operations. A 'defense contractor,' as defined by the Code of Federal Regulations, is 'any individual, firm, corporation, partnership, association, or other legal non-Federal entity that enters into a contract directly with the DOD to furnish services, supplies, or construction' (see 32 C.F.R. 158.3, 'Definitions'). Within the defense policy community, the term 'contractor' is commonly used in two different contexts. The word can describe the private companies with which DOD contracts to provide goods and services. It can also describe individuals hired by DOD--usually through private companies, which are also considered contractors in the previous context--to perform specific tasks. The term 'contractor' does not refer to military servicemembers, civilian DOD career employees, or civilian political appointees."
CRS In Focus, IF10600
Congressional Research Service: https://crsreports.congress.gov/