what are the animal categories
No, animal classes are not like the classes people have at school! An animal class is made up of animals that are all alike in important ways. Scientists have grouped animals into classes to make it easier to study them. There are many different animal classes and every animal in the world belongs to one of them. The five most well known classes of vertebrates (animals with backbones) are mammals, birds, fish, reptiles, amphibians. They are all part of the phylum chordata -- I remember  chordata  by thinking of spinal chord.