Insects have a complex body structure divided into three main parts: the head, thorax, and abdomen. The head contains sensory organs like antennae and compound eyes, as well as the mouthparts used for feeding. The thorax is responsible for movement and has three pairs of legs and, in many species, two pairs of wings. The abdomen houses vital organs for digestion and reproduction. Insects have an exoskeleton made of chitin, which provides protection and support. This hard outer layer must be shed periodically through a process called molting to allow for growth.