This chapter discusses pain and relief from pain, which is an intensely subjective experience, and is therefore difficult to describe. Pain serves a protective function by making us aware of actual or impending damage to the body. The receptors for fast pain are sensitive to mechanical or thermal stimuli of noxious strength. The receptors for slow pain are sensitive not only to noxious mechanical and thermal stimuli but also to a wide variety of chemicals associated with inflammation. Pain receptors are found maximally in the skin, but significant numbers are also present in the periosteum, arterial walls, joint surfaces, falx cerebri and the tentorium. The most conspicuous part of the body which has no pain receptors at all is the brain. The body has an in-inbuilt system for reducing the intensity of pain. Stimulation of several areas of the central nervous system produces a specific analgesic response.