ABSTRACT
Childhood and adolescence are distinct periods within the lifespan, although exact age ranges can vary slightly based on the source. Childhood is often divided into at least three sub-stages. The infant/toddler years (ages 0-3) are marked by significant physical and cognitive development as well as dependence on caregivers. These trends continue during the preschool years (ages 3-5) as children develop more independence and start preschool. The school-age years (ages 6-12), also called middle childhood, are signified by increases in independence, cognitive development, physical growth, social engagement, and maturation. Adolescence, also known as the teenage years, is a time of raging hormones, increased social and romantic interests, marked desire for independence and autonomy, and preparation to leave the family of origin. The World Health Organization (WHO) generally considers adolescence to include ages 10-19, but has also noted that age may be more related to the biological changes occurring during adolescence than the social and emotional changes.
