Nests are built by animals to stay in.
Not all animals build and stay in nests.
Nests can be built in places like trees, burrows in the ground or in caves.
Nests also serve to protect the young of animals from danger and to keep them safe.
Nests may be home to just one animal or to millions of animals.
The most famous nest builders are birds, but some fish build nests of bubbles in water.
Nests can be made out of many things including twigs and leaves.
Some animals use their saliva to hold their nests together.