Residency or postgraduate training is a stage of graduate medical education. It refers to a qualified physician, podiatrist, dentist, optometrist, veterinarian, or pharmacist (one who holds the degree of MD, DPM, DDS, DMD, DVM, DO, OD, PharmD, BDS, or BDent; or MB; BS, MBChB, or BMed) who practices medicine, usually in a hospital or clinic, under the direct or indirect supervision of a senior clinician registered in that specialty such as an attending physician or consultant. In many jurisdictions, successful completion of such training is a requirement in order to obtain an unrestricted license to practice medicine, and in particular a license to practice a chosen specialty. An individual engaged in such training may be referred to as a resident, house officer, registrar or trainee depending on the jurisdiction. Residency training may be followed by fellowship or sub-specialty training.