Some people enjoy spending a lot of time in their homes to make them nice places to live. This is called "nesting" or "cocooning."
Birds build nests out of sticks to hold their eggs and baby birds.
Some insects build cocoons around themselves for protection while they grow and change.
Nests and cocoons provide security for wildlife. So people like the idea of nests and cocoons, too.
The terms cocooning and nesting became popular more than twenty years ago.
They describe people buying their first homes and filling them with many things. These people then had children.
Now these children are grown and have "left the nest." They are in college. Or they are married and starting families of their own far away.
Now these parents are living alone without children in their "empty nest." They have become "empty nesters."
