Developmental stages refer to the distinct phases of growth and change that individuals experience throughout their lives. These stages are often categorized into periods such as infancy, childhood, adolescence, and adulthood. Each stage is characterized by specific physical, cognitive, and emotional developments that influence a person's abilities and behaviors. In psychology, various theories, such as those proposed by Jean Piaget and Erik Erikson, outline how individuals progress through these stages. For example, Piaget focused on cognitive development, while Erikson emphasized psychosocial challenges. Understanding these stages helps in recognizing the typical milestones and variations in human development.