The process of providing warmth to eggs that hatch is known as [[1]] or incubation.

Usually, the hen sits on the eggs to provide sufficient warmth. This process is called brooding. 

Natural incubation or brooding is the simplest way of hatching a small number of eggs. 

A broody hen (chicken) will incubate her own eggs or those of another hen or a duck. 

Broody hens may refuse to leave the eggs to eat or drink.