These words all denote persons engaged in treating sick or injured people. Doctor , physician and surgeon are all licensed practitioners of medicine who have received one or more degrees from a university medical school. Doctor is the most general term and is applied to all who have qualified in medicine, whether they maintain a practice or are engaged in research work or other fields in which they have no contact with patients. The title is a courtesy one, since the majority of doctors hold the degree of M.B. (Bachelor of Medicine). The degree of M.D. (Doctor of Medicine) is the highest awarded by a university medical faculty and is generally ranked higher than the degree of Ph.D. (Doctor of Philosophy). Few doctors in practice have achieved the academic distinction of M.D. (In the united States, all who qualify to practise medicine are automatically awarded the degree of M.D., but this does not correspond to the M.D. conferred by Australian and New Zealand universities.) Dentists and veterinarians also are often known by the title of doctor . A general practitioner is a doctor with a wide general knowledge of medicine who practises in a community and who is the doctor first consulted by a sick person. Physician is a term which also may be applied to a doctor in general practice, but more often it means one who has taken a higher medical degree and to whom patients are referred by a general practitioner when necessary. Such a physician is known as a specialist , e.g., a heart specialist . As well as seeing patients in his or her consulting rooms, a physician is usually on the staff of a hospital.

In recent years medical knowledge has become such a vast field that more and more doctors are undergoing postgraduate training and are restricting their practice to specific fields such as paediatrics, dermatology, gynaecology and obstetrics, urology, radiology, psychiatry, etc. To these also the term specialist may be applied. To practise in a chosen speciality, a doctor will have studied for and passed an examination for a university diploma in that speciality, or for fellowship or membership of the learned college or society relating to it, such as the College of Radiologists of Australasia.

A surgeon is primarily concerned with diseased conditions or injuries requiring operative procedures. Thus, all surgeons are specialists in a general sense, in that they devote themselves to the surgical side of medicine, but some are specialist surgeons who concentrate on particular parts of the body or on certain clearly demarcated fields of surgery: an orthopaedic surgeon ; a plastic surgeon .

An osteopath is a practitioner of a school of healing known as osteopathy, which stresses the importance of the musculoskeletal system and its proper functioning as a basis for health. Often, his preferred method of treatment is manipulation of the muscles and bones, especially the backbone. A chiropractor puts a similar emphasis on the spinal area as basic to health and treats patients by the manual adjustment and manipulation of this and related areas.