Child is a person between the ages of about 18 months and 10 to 12 years. Childhood is the period of development between infancy and adolescence. Infancy extends from birth to about 18 months of age. Adolescence begins at about 10 to 12 years and lasts until young adulthood.

Childhood is a period of transformation that involves a variety of physical, psychological, and social processes. These processes largely determine the type of adult that a child will become. During childhood, most boys and girls nearly double in height and quadruple in weight. They also begin to develop sexually. But childhood involves far more than physical growth and development. It involves significant changes in a child's behavior, thought processes, emotions, and attitudes. Parents, siblings (brothers and sisters), and other family members traditionally play vital roles in guiding a child s development. But as childhood progresses, boys and girls become increasingly independent and responsible for their own well-being.

Cultures throughout the world differ in their attitudes, beliefs, and traditions relating to childhood. Some cultures, for instance, define childhood as the period that lasts from birth until sometime past the age of 20. Some of these cultures do not recognize infancy and adolescence as distinct stages of development. Cultures also differ in the skills, values, and personality traits that they seek to develop in children.

Every child is a unique individual, with his or her own talents, characteristics, personality, and background. Despite these differences, many of the basic stages, experiences, and challenges of childhood are similar throughout the world.