Insects are well known invertebrates with jointed legs .They have segmented bodies .Ant ,butterfly , bee cockroach ,etc are the examples of insects.
In order to answer this question we must look at where insects fit in the animal kingdom. The animal kingdom is divided into several groups called phyla. An example of a phylum is the Chordata, which holds all the backboned a
Insects are arthropods
Arthropods are characterised by having the following features:
a hard external skeleton (called a exoskeleton)
a segmented body
at least three pairs of jointed legs
The Arthropoda is divided into a number of classes. These include the:
Crustacea (crabs, crayfish, prawns)
Arachnida (spiders, mites, scorpions)
Myriapoda (millipedes & centipedes)
Insecta (insects)
Successful and important
The insects have proved to be the most successful arthropods. There are far more species in the class Insecta than in any other group of animals. These amazingly diverse animals have conquered all the environments on earth except for the frozen polar environments at the highest altitudes and in the immediate vicinity of active volcanoes. Insects are the only invertebrates (animals without backbones) with wings. Much of their success results from their ability to fly and colonise new habitats. The study of insects is called entomology and entomologists are scientists who study insects.
Insects play a very important role in the web of life, in every environment. Some of their jobs include pollinating flowering plants, being a source of food for insectivorous animals and assisting in the decomposition of plants and animals.
Insect classification
Modern insect classification divides the Insecta into 29 orders, many of which have common names. Some of the more common orders are:
Mantodea - praying mantids
Blattodea - cockroaches
Isoptera - termites
Siphonaptera - fleas
Odonata - dragonflies and damselflies
Dermaptera - earwigs
Diptera - flies
Lepidoptera - butterflies and moths
Orthoptera - grasshoppers, katydids, crickets
Coleoptera - beetles
Hymenoptera - wasps, bees, ants, sawflies