Talking about insects means, in reality, to consider a much larger group: that of arthropods.
This includes four different classes:
• Chelicerata. It includes spiders, mites, scorpions, limuli and other organisms characterized by the presence of a pair of appendages, called chelicerae, and eight legs.
• Myriapoda. Includes centipedes and other organisms with a high number of trunk segments, many of which carry one or two pairs of legs.
• Crustacea. Includes lobsters, crabs, prawns and other organisms, mainly aquatic, characterized by having two pairs of preoral appendages (antennae and antennae) and 10 legs (a pair of front legs transformed into pincers, the claws).
• Hexapoda. It includes insects, collembola, proturi and dipluri, all organisms that carry three pairs of legs.