Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.A private military company (PMC) provides specialized expertise or services of a military nature, sometimes called or classified as mercenary ("soldiers for hire"). Such companies are equally known as private military contractors, Private Security Contractors (PSCs), Private Military Corporations, Private Military Firms, Military Service Providers, and generally as the Private Military Industry. The services and expertise cover those typically found in governmental military or police forces, but most often on a smaller scale. While PMCs often provide services to train or supplement official armed forces in service of governments, they are also employed by private firms. However, contractors who use offensive force in a war zone could be considered unlawful combatants, thereby referring to the "concept" being implicitly mentioned in the Geneva Conventions and explicitly specified by the Military Commissions Act.