Medical school in the United States is a graduate program with the purpose of educating physicians in the undifferentiated 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, while some confer a Doctor of Podiatric Medicine (DPM) or Doctor of Osteopathic Medicine (DO) degree. 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.