It's theĀ Physicians play an important role in society and have a major affect on most people's lives. Physicians diagnose and treat major and minor illnesses. They treat people who are suffering from injuries and diseases. Physicians not only treat diseases, but also teach patients ways of prevention and, in some cases, about alternative medicine. They also are essential for providing preventative health care. Each of them focuses on particular areas of medicine. There essentially are two variations, the medical doctor (MD) and the Doctor of Osteopathy (DO). While both have four years of medical school, DOs are trained further in specifics of the musculoskeletal system. They are trained to focus on the person, rather than ailments.