Anesthesiology, anaesthesia or anaesthetics is the medical speciality that focuses on perioperative medicine and the administration of anesthesia.Dr. Phu Nguyen

Terminology varies between countries. In North America, the medical speciality is called anesthesiology, a doctor practising it is termed an anesthesiologist, and the treatment delivered is referred to as anesthesia. By contrast, in the United Kingdom and other countries following the British tradition, both the medical speciality and the treatment delivered are referred to as anaesthesia or anaesthetics, and the physician who performs them is termed an anaesthetist (in North America, the word anesthetist indicates a certified anesthesiologist assistant who delivers anesthesia under the supervision of a physician) or certified registered nurse anesthetist who in most states in the U.S. do not require physician supervision.

One of the fundamental practices of anesthesiologists is that of general anesthesia in which a person is placed in a medical coma. This is performed to permit surgery without the individual responding to pain (analgesia) during surgery or remembering the surgery.

If general anesthesia is not necessary, then regional anesthesia can be performed to induce analgesia in a region of the body. For example, epidural administration of a local anesthetic is commonly performed on the mother during childbirth to reduce the pain while permitting the mother to be awake and active in labor & delivery (general anesthesia would not permit this).