Anesthesia is the process of blocking the perception of pain and other sensations. This allows patients to undergo surgery and other procedures without the distress and pain they would otherwise experience. There are several forms of anesthesia including: 1) general anesthesia — with reversible loss of consciousness 2) local anesthesia — with reversible loss of sensation in a (small) part of the body by localized administration of anesthetic drugs at the affected site. 3) regional anesthesia — with reversible loss of sensation and possibly movement in a region of the body by selective blockade of sections of the spinal cord or nerves supplying the region.