Your doctor says you need surgery. Most surgery, no matter how intensive or minor, requires the administration of anesthesia.
Anesthesia is a drug that is introduced by a qualified medical practitioner that induces a loss of sensation in the body. There are several types of anesthesia, according to the American Society of Anesthesiologists.
Local anesthesia is injected into the tissue to numb a specific location of the body, like when the dentist numbs your mouth before oral surgery or other dental procedures.
Regional anesthesia is injected into a cluster of nerves to numb an area of your body before surgery, like when a mother is given an epidural before childbirth.
General anesthesia might be a gas or vapor introduced through a breathing mask or a tube or may be introduced through the veins to make you unconscious. The level of anesthesia is monitored by a qualified/certified practitioner to make sure you are asleep deeply enough and for long enough.