To obtain the degree, people need to pass a special exam, called a doctorate, or by writing a thesis. The requirements vary according to the subject-matter. A doctorate is usually regarded as a higher degree than a bachelor's degree (such as B.A. or B.Sc)
People who have a doctor's degree may use the title "doctor", though in practice it is often used only by medical doctors. Medical doctors examine, diagnose and treat patients. They can specialize in a number of medical areas, such as pediatrics, anesthesiology or cardiology, or they can work as general practice physicians. Becoming a medical doctor requires a doctoral degree in medicine and participating in clinical training. Medical doctors need a licence, and certification may also be required for many specialists.
- Medical doctor or Doctor of Medicine, a person who practices medicine. Degrees vary: M.D. is common in the United States; MRCP is common in the UK, and they are addressed as "doctor" whatever the degree.
- Juris Doctor or Doctor of Law
- Doctor of Philosophy a general degree for any subject which offers a doctorate for research and presentation of a thesis.
- Universities may award doctorates to people who have done a lot in their fields of study: these are called honorary doctorates. There is no set rule for this. Very often, these are abbreviated "Doctor h.c." (for "honoris causa").