Human development refers to the process of growth and change that individuals experience throughout their lives. This includes physical, cognitive, emotional, and social development, which are influenced by various factors such as genetics, environment, and culture. Key stages of human development are often categorized into childhood, adolescence, adulthood, and old age, each with distinct characteristics and challenges. The study of human development is important for understanding how people evolve and adapt over time. It encompasses theories from notable figures like Jean Piaget, who focused on cognitive development, and Erik Erikson, who emphasized psychosocial development. These theories help in identifying the needs and behaviors of individuals at different life stages.