Animals are classified into many different groups based on their characteristics. The farther you go down, the more specific the characteristics get.
The most general grouping. The animal kingdom includes all animal life. Their are kingdoms for plants, fungi, protists, and bacteria as well. All members of the animal kingdom depend on foods to survive. Most animals are able at some point in their lives to move freely through air or water, so that they may find food and another animal to mate with. All animals have sensory organs and nervous systems. The whole kingdom is divided in two: those with backbones and those without (AKA vertebrates and invertebrates
The animal kingdom divides into 40 smaller groups called Phyla (Singular, phylum). Animals are put into their phylum according to their main features. For example, the Chordata phylum, which contains all animals with backbones, or the Crustacea phylum, which contains invertebrates with jointed legs and two pairs of antennae
Phyla are subdivided into classes. The chordates phylum separates into fish, mammals, birds, reptiles, and amphibians. We, as humans, belong to Mammalia (Mammals)
The subdivision of classes. The Mammalia Class separates into meat-eaters, egg-layers, insect-eaters, rodents, marsupials, etc.
Families further split up the groups. One example is Felidae (cats).
Animals that belong to same genus are closely related but do not breed together. The first name in an animals scientific name is its genus
The final grouping. Animals in the same species or subspecies can breed together. The second part of an animals scientific name is its species. If an animal has a third part to its scientific name, that part indicates subspecies.