Zoology is a branch of biology, a science concerned with the study of the animal kingdom. It deals with the biology of the species seen within the large groups, their morphologies without insisting too much on their internal anatomies. To encourage the effort of memory, the scientific concepts of species, genera, families and orders are systematically dissected into their Greek and Latin etymological roots and explained. It allows to illustrate the simple single-celled animal and the multicellular organism with increasingly complex structure. This science allows to learn the natural behavior of animals, as well as their habitats and the need to maintain balance in our environment.