Too hot! As our fingertips graze the hot stove, their thermal receptors sound an alarm. The message races at 300 kilometers an hour through the nervous system to the brain, where it gets immediate attention. The muscles receive an order to pull those fingers away from the surface.
Such messages--encoded as electrical impulses--constantly stream through our nervous system. They not only prevent us from burning our fingers on the hot stove but also enable our very survival.