Final answer:
Insects are part of Hexapoda and possess three pairs of jointed legs, distinguishing them from other arthropods. These legs, along with antennae and specialized mouthparts, are essential for their movement and feeding. The name 'Hexapoda' emphasizes the six-legged characteristic of insects.
Step-by-step explanation:
Insects, as part of the subphylum Hexapoda, have bodies organized into three tagmata: head, thorax, and abdomen. Their name, Hexapoda, literally means "six feet" and refers to their three pairs of jointed legs attached to the thorax. These appendages are crucial for their locomotion and are a defining characteristic of insects compared to other arthropods. In addition to the jointed legs, insects also have a pair of antennae for sensing chemicals, specialized mouthparts for feeding, such as mandibles and maxillae, and in the case of the subclass Pterygota, wings for flight.
The insect order Thysanura, which includes bristletails, exhibits "primitively wingless" insects. Other orders of insects are either winged or descendants of winged ancestors. Across the diverse world of arthropods, which includes not only insects but also crustaceans and myriapods, the adaptive and evolutionary modifications of these appendages have allowed for a variety of ecological roles and survival strategies.