Final answer:
All mammals are characterized by hair or fur and mammary glands.
Step-by-step explanation:
All mammals are characterized by two main features:
- Hair or fur: Mammals have hair or fur on their bodies, which helps them regulate body temperature and protect their skin.
- Mammary glands: Mammals have mammary glands that produce milk to nourish their young. This is a unique characteristic of mammals.
Learn more about Characteristics of mammals