Adolescence is described as the transitional period between childhood and adulthood where individuals experience significant physical, mental, emotional and social changes. It begins with the onset of puberty between ages 10-14 for girls and 12-16 for boys and lasts until sexual maturity and independence from parental authority is achieved, around ages 18-21. The document outlines how adolescence is a crucial developmental period where identities and worldviews are shaped, but also a time of stress, conflicts and adjustments to changes in relationships with peers and family.