What are mammals? What are their characteristics?

Mammals are warm-blooded, hairy animals that give birth to babies and produce milk to feed them.

The characteristics of mammals are:

1. They have hair on their body.
2. They give birth to babies and have mammary glands that produce milk for nourishing their young ones.
3. Most mammals have external ears, nose and specialised teeth
4. They breathe through lungs.
5. They have a four-chambered heart.
6. The sexes are separate — male and female.