Anesthesia is the loss of feeling or awareness. It has a long and storied history going back to antiquity. A general anesthetic puts the person to sleep while a local anesthetic causes loss of feeling in a part of the body such an area of skin or perhaps a tooth without affecting consciousness. Regional anesthesia numbs a larger part of the body. e.g. an arm or leg, without affecting consciousness. Conduction anesthesia encompasses both local and regional anesthetic techniques. Many surgical procedures can be done with conduction anesthesia without significant pain. In many situations, such as a C-section, conduction anesthesia (called a spinal block) is safer and therefore preferable to general anesthesia. However, there are also many types of surgery in which general anesthesia is clearly appropriate.
Anesthesiology is the branch of medicine specializing in the use of drugs or other agents to cause insensibility to pain. Anesthesiology may also include continuity of patient care involving preoperative evaluation, operative and postoperative care and the management of personnel who support these activities. The subspecialities within anesthesiology include cardiothoracic anesthesiology, critical care, neuroanesthesia, obstetrical anesthesiology, pain management, pediatric anesthesiology, and ambulatory anesthesia. There is a difference between an anesthesiologist and an anesthetist. An anesthesiologist has a doctorate whereas an anesthetist does not. An anesthesiologist is a physician (or, less often, a dentist) who is specialized in the practice of anesthesiology while an anesthetist is a nurse or technician trained to administer anesthetics.