why do we have goosebumps?

Goosebumps are tiny elevations of the skin. These bumps are caused by a contraction of miniature muscles that are attached to each hair. Each contracting muscle creates a shallow depression on the skin surface, which causes the surrounding area to protrude. The contraction also causes the hair to stand up. The reason is the subconscious release of a stress hormone called adrenaline. Adrenaline is produced by adrenal glands. Which causes the contraction of skin muscles and influences other body reactions. This hormone is released when the animal is in cold or facing a stressful situation, preparing the animal for flight-or-fight reaction. It is released when in fear and feels strong emotions, such as anger or excitement.