The
eyebrow is an area of thick, delicate hairs above the
eye that follows the shape of the lower margin of the
brow ridges of some
mammals. Their main function is hypothesized to prevent sweat, water, and other debris from falling down into the eye socket, but they are also important to
human communication and
facial expression. It is not uncommon for people to modify their eyebrows by means of hair addition, removal and makeup.