In the medical profession, a general practitioner (GP) is a medical doctor who treats acute and chronic illnesses and provides preventive care and health education to patients. A general practitioner manages types of illness that present in an undifferentiated way at an early stage of development, which may require urgent intervention. The holistic approach of general practice aims to take into consideration the biological, psychological, and social factors relevant to the care of each patient's illness. Their duties are not confined to specific organs of the body, and they have skills in treating people with multiple health issues. They are trained to treat patients of any age and sex to levels of complexity that vary between countries. The role of a GP can vary greatly between (or even within) countries. In urban areas of developed countries, their roles tend to be narrower and focused on the care of chronic health problems; the treatment of acute non-life-threatening diseases; the early detection and referral to specialised care of patients with serious diseases; and preventive care including health education and immunisation. Meanwhile, in rural areas of developed countries or in developing countries, a GP may be routinely involved in pre-hospital emergency care, the delivery of babies, community hospital care and performing low-complexity surgical procedures. In some healthcare systems GPs work in primary care centres where they play a central role in the healthcare team, while in other models of care GPs can work as single-handed practitioners.