Anesthesia is a medical treatment that prevents patients from feeling pain during surgery. It allows people to have procedures that lead to healthier and longer lives.To produce anesthesia, doctors use drugs called anesthetics. Scientists have developed a collection of anesthetic drugs with different effects. These drugs include general, regional, and local anesthetics. General anesthetics put patients to sleep during the procedure. Local and regional anesthetics just numb part of the body and allow patients to remain awake during the procedure. Depending on the type of pain relief needed, doctors deliver anesthetics by injection, inhalation, topical lotion, spray, eye drops, or skin patch. General anesthesia affects the whole body, making patients unconscious and unable to move. Surgeons use it when they operate on internal organs and for other invasive or time-consuming procedures such as back surgery. Without general anesthesia, many major, life-saving procedures would not be possible, including open-heart surgery, brain surgery, and organ transplants.