The defense industry, also called the military industry, is comprised of government and commercial industry involved in research, development, production, and service of military equipment and facilities. It includes:

• Defense contractors: business organizations or individuals that provide products or services to a defense department of a government.
• The Arms industry, which produces guns, ammunition, missiles, military aircraft, and their associated consumables and systems.

• Private military contractors: private companies that provide logistics, manpower, and other expenditures for a military force.
• The Military-industrial complex, which is generally the combination of the U.S. armed forces, arms industry and associated political and commercial interests, although it can also be used to describe any such relationship of industry and military.
• European defence procurement, which is more or less analogous to the U.S. "military-industrial complex."