Childhood is the age span ranging from birth to adolescence. In developmental psycology, childhood is divided up into the developmental stages of toddlerhood (learning to walk), early chldhood (play age), middle childhood (school age), and adolescence(post-puberty).The term childhood is non-specific and can imply a varying range of years in human development. Developmentally, it refers to the period between infancy and adulthood. In common terms, childhood is considered to start from birth. Some consider that childhood, as a concept of play and innocence, ends at adolescence. In many countries, there is an age of majority when childhood officially ends and a person legally becomes an adult. The age ranges anywhere from 13 to 21, with 18 being the most common.