Pain is a sensation of suffering due to some form of stimulation of nerve endings. Pain is characterized by: the location: identified by anatomy (e.g. back, chest, head, etc.) the quality: local, diffuse, constant, intermittent, burning, shooting, gnawing, sharp, dull, throbbing, etc radiation: the distribution from the place where it is felt worst frequency (continually, occasionally, etc.) triggering agents: exercise, emotional state, ingestion of certain food, etc. associated symptoms: shortness of breath (sometimes with chest pain), photophobia (often with migraine), bloating (often with gallstones), etc.