Adolescence is the phase of life between childhood and adulthood, from ages 10 to 19. Young adolescents are those and 10-14 years, while older adolescents are those 15-19 years.  It is a unique stage of human development and an important time for laying the foundations of good health. Adolescents experience rapid physical, cognitive and psychosocial growth. This affects how they feel, think, make decisions, and interact with the world around them.