The elytra primarily serve as protection for the hindwings underneath, which are used for flying. In some groups, the elytra are fused together, rendering the insect flightless. Some of the ground beetles (family Carabidae) are a good example of this.
The term is also used to describe the hard scales of some polychaete worms, notably the Polynoidae. These outgrowths of the body wall are distinguished from chaeta, which grow from follicles and thus possess roots.