Emergency medicine is a subspecialty that focuses on patients who need immediate and often intensive care. These physicians must be able to handle medical problems quickly to avoid potential complications with their patients. With their knowledge of emergency medicine comes knowledge about many other types of medicine, as they must be able to respond to patients who present a variety of symptoms and problems. They will also have a thorough understanding of emergency medical devices.

An oncologist is a medical professional who has the education and training necessary to diagnose and treat various type of cancers. Oncologists practice in hospitals and medical centers, university hospitals, and research organizations. In addition to diagnosing and treating tumors and cancer, they conduct research to learn more about cancer and how it acts in the body to help develop new treatment options.

An internist or Internal Medicine doctor is someone who specializes in diagnosing and treating illnesses, diseases, and health problems. Most internists are also primary care doctors and treat patients on a regular basis. They can diagnose and treat common illnesses or more serious problems. Most people see an internist regularly. Those with chronic illnesses may do so on a monthly or even weekly basis. Internists are the most common types of doctors.