Medical school in the United States is a graduate program with the purpose of educating physicians in the field of medicine. Such schools provide a major part of the medical education in the United States. Most medical schools in the US confer upon graduates a Doctor of Medicine (MD) degree, although some confer a Doctor of Osteopathic Medicine (DO) degree or a Doctor of Podiatric Medicine (DPM) degree. A few offer combined programs where graduates earn both a bachelor's degree and an MD or DO. Most schools follow a similar pattern of education, with two years of classroom and laboratory based education, followed by two years of clinical rotations in a teaching hospital where students see patients in a variety of specialties. After completion, graduates must complete a residency before becoming licensed to practice medicine.