Doctor Dinner, Anesthesiologist of New York Presbyterian Hospital Weill Cornell Medical Center, explains the difference between regional and general anesthesia, and goes into the 5 levels of general anesthesia.

Doctor Dinner: Anesthesia is a broad term. There are many ways of providing that type of service to a patient and most patients certainly appreciate that when they're going for surgery that they want to be "anesthetized." Being anesthetized can be where one is actually awake and under regional anesthesia. For instance, people have heard the term spinal or epidural anesthesia or a regional anesthetic such as a block, and those types of anesthetics are performed sort of custom tailored to the patient's own individual needs, their physiology, their underlying diseases, the surgeon's needs and what is proper, fitting and safe. So the term general anesthesia generally implies five specific states that the patient is in. One, where they're not conscious. Two, where they don't move; they're essentially paralyzed or their muscle movements are inhibited. Three, where they don't feel pain. Four, where they don't remember. Five, where their vital functions - we call it the autonomic nervous system, is tranquilized and controlled. So those five things are what general anesthesia basically implies.