Over four thousand different types of mammals exist in the world. Many favourite pets and farm animals are mammals, but what makes them alike? Learn about the mammal classification including mammals' common traits, where they live, and which ones can fly.

Over four thousand different types of mammals exist in the world. Many favourite pets and farm animals are mammals, but what makes them alike? Learn about the mammal classification including mammals' common traits, where they live, and which ones can fly.