A specialty in medicine is a branch of medical practice. After completing medical school, physicians or surgeons usually further their medical education in a specific specialty of medicine by completing a multiple year residency to become a medical specialist.History of medical specializationTo a certain extent, medical practitioners have always been specialized. According to Galen, specialization was common among Roman physicians. The particular system of modern medical specialities evolved gradually during the 19th century. Informal social recognition of medical specialization evolved before the formal legal system. The particular subdivision of the practice of medicine into various specialities varies from country to country, and is somewhat arbitrary.Classification of medical specializationMedical specialties can be classified along several axes. These are: Surgical or internal medicine Age range of patients Diagnostic or therapeutic Organ-based or technique-based Throughout history, the most important has been the division into surgical and internal medicine specialties. The surgical specialties are the specialties in which an important part of diagnosis and treatment is achieved through major surgical techniques. The internal medicine specialties are the specialties in which the main diagnosis and treatment is never major surgery. In some countries Anesthesiology is classified as a surgical discipline, since it is vital in the surgical process, though anesthesiologists never perform major surgery themselves.