For an aircraft to remain airworthy and safe to operate, it must undergo regular procedures to ensure that all components and systems are functioning as intended or are repaired or replaced as necessary. Maintenance, repair, and overhaul (MRO) refers to the maintenance processes that aircraft undergo, those of which are typically carried out at a major maintenance facility. Aircraft of all types undergo MRO procedures on a regular basis, be they airliners, military aircraft, general aviation trainers, and other types. As maintenance, repair, and overhaul enhance the longevity of an aircraft and its health, it can be useful to understand what it is and where it is carried out.