Anesthesiology is a branch of medicine that focuses on pain relief during and after surgery. This treatment is called anesthesia. Practitioners of anesthesiology are called anesthesiologists or, in some countries, anaesthetists.

Anesthesiologists often also undertake non-surgical pain relief and critical care management.

Anesthesiologists are physicians who provide medical care to patients in a wide variety of (usually acute) situations. This includes preoperative evaluation, consultation with the surgical team, creation of a plan for the anesthesia tailored to each individual patient, airway management, intraoperative life support and provision of pain control, intraoperative diagnostic stabilisation, proper post-operative management of patients. Outside the operating room, anesthesiologists/anesthesists spectrum of action includes with intrahospitalar or extrahospitalar emergencies, intensive care units, acute pain units and chronic pain consultations. Because anesthesiologists/anesthetists are physicians, in contrast to other anesthesia providers, they are able to utilize their extensive knowledge of physiology, pharmacology and diseases to guide their decision making.