Goose bumps, goosebumps or goose-pimples[1] (also called chill bumps[citation needed]) are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold or experiencing strong emotions such as fear, euphoria or sexual arousal.[2][3]
The formation of goose bumps in humans under stress is considered by some to be a vestigial reflex,[4] though visible piloerection is associated with changes in skin temperature in humans.[5] The reflex of producing goose bumps is known as piloerection or the pilomotor reflex, or, more traditionally,[6]horripilation. It occurs in many mammals; a prominent example is porcupines,[7] which raise their quills when threatened, or sea otters when they encounter sharks or other predators.