Insects are a type of invertebrate animal without a spine. They are arthropods with segmented bodies, ectothermic traits ("cold-blooded"), and an exoskeleton. Insects have a unique design with three body sections, six legs, two antennae, and sometimes wings. They are a class within arthropods called Insecta, characterized by their segmented bodies and legs, exoskeletons, head, thorax and abdomen structure, and six legs.