Hospital Corpsman (HM) is a rating in the Unite States Navy and a member of the Navy's Hospital Corps. Hospital corpsmen serve as enlisted medical specialists for the United States Navy and United States Marine Corps. Hospital corpsmen serve in a wide variety of capacities and locations, including shore establishments such as naval hospitals and clinics, aboard ships as the primary medical caregivers for sailors while underway, or with Marine Corps units as battlefield corpsmen. The colloquial form of address for a corpsman is "Doc".