Here are the broad categories of animals, how we organize them.

Mammal

• A mammal has hair or fur at some point in its life.
• It is a vertebrate, has a backbone.
• The babies are born live, not hatched from eggs, and drink milk from their mother.

Reptile

• They are cold blooded, their temperature relies on their environment.
• They have scales.
• They lay eggs.

Amphibian

• They are cold blooded.
• They live in water and on land.

Fish

• They live in water.
• They breathe with gills instead of lungs.

Bird

• They have feathers.
• They are vertebrates.
• They lay eggs.

Animal classification is about placing animals into categories such as these based on their characteristics. It helps us know more about each animal because they probably have many things in common with others of the same classification. These characteristics are mostly true, but you should know, there are exceptions to these classification rules. For instance, the platypus is a mammal but lays eggs, and there are some snakes, like the sea snake, that give birth to live snakes.