This document discusses psychology and human development. It defines psychology as the study of human behavior and existence. It explains that development refers to progressive changes that occur as a result of maturation and experience, with the goal of enabling individuals to adapt to their environment. It also outlines the key biological, cognitive, and socioemotional processes involved in development across the lifespan from infancy to late adulthood. Studying developmental psychology helps describe changes by age and experience in physical, intellectual, and personality growth.