Residency is a stage of graduate medical training. A resident or house officer is a physician (one who holds the degree of M.D., D.O., MBBS, MBChB, or BMed) who practices medicine usually in a hospital or clinic under the direct or indirect supervision of an attending physician. Successful completion of a residency program is a requirement to obtaining an unrestricted license to practice medicine in many jurisdictions. Residency training may be followed by fellowship or "sub-specialty" training.
Whereas medical school teaches physicians a broad range of medical knowledge, basic clinical skills, and supervised experience practicing medicine in a variety of fields, medical residency gives in-depth training within a specific branch of medicine. A physician may choose a residency in anesthesiology, ophthalmology, cardiothoracic surgery, dermatology, emergency medicine, family medicine, internal medicine, neurology, neurosurgery, obstetrics and gynecology, otolaryngology, pathology, pediatrics, plastic and reconstructive surgery, psychiatry, physical medicine and rehabilitation, radiology, radiation oncology, oral and maxillofacial surgery, general surgery, urology or other medical specialties.