Final answer:
Childhood is defined as the stage between birth and adolescence, consisting of infancy, early childhood, middle childhood, and pre-adolescence.
Step-by-step explanation:
Biologically, childhood is defined as the stage of a human organism between birth and adolescence. The first year of life is called infancy and is covered in the concept Infancy. The remaining years until adolescence are loosely divided into early childhood (one to five years), middle childhood (six to ten years), and pre-adolescence (11-12 years).