Insects are a major group of arthropods and are the most diverse group of animals on the planet with over a million described species; more than all other animal groups combined.
An insect can be described as an air breathing animal with a hard jointed external skeleton (exoskeleton). An insect also has a body divided into 3 parts: the head with one pair of antennae, the thorax which carries 3 pairs of legs and usually 2 pairs of wings, and the abdomen which contains the guts and reproductive organs.
Insects include ants, bees, beetles, bugs, butterflies, flies, moths, wasps and others. Insects are the only arthropod to have developed flight which has played an important and vital role in their success. The study of insects is called entomology.