A mammal has hair,is warm blooded 
and feeds it's young milk.

3 kinds of mammals: Monotremes,
Marsupials and Placental.

Monotremes:Egg-Laying mammals.
Echidna, Platypus.

Marsupials: Young are born in 
an extremely immature state. 
Most female marsupials have 
pouches. Koala, Kangaroo.

Placental: Young are born at a 
relatively advanced stage.
Most mammals are placental, 
cats, dogs and people.