This document provides an overview of the animal kingdom. It discusses that animals are eukaryotic, heterotrophic and multicellular organisms that lack cell walls. It notes that 95% are invertebrates without backbones, while 5% are vertebrates with backbones. The seven essential functions of animals are then outlined as feeding, respiration, circulation, excretion, response, movement and reproduction. Trends in animal evolution discussed include cell specialization, early development through germ layers, body symmetry and cephalization. The major phyla of animals are then briefly described.