A newborn is a baby in its first few weeks of life, usually the first month after birth. When you see a newborn, you're looking at someone brand new to the world: eyes barely able to focus, tiny fists curled tight, spending most of their time sleeping and eating.

Newborns are incredibly fragile and dependent. They can't hold up their own heads, can't see clearly beyond about a foot away, and need round-the-clock care. Their parents have to support their heads carefully when holding them, feed them every few hours, and keep them warm since newborns can't regulate their body temperature well yet.

You might hear someone say “newborn baby,” though that's a bit redundant since all newborns are babies.

Animals have newborns too. A newborn calf can stand within an hour of birth, while newborn puppies are born blind and helpless like human babies. The needs of a newborn vary wildly across species: some animals are ready to run from predators immediately, while others need weeks or months of intensive care.

When people say someone has “newborn energy,” they usually mean that exhausted, overwhelmed feeling that comes from caring for a baby who wakes up every two hours, day and night.