Growth and development in children occurs rapidly from birth through 12 years of age. There are several key stages of development: prenatal, infancy, early childhood, middle childhood, and late childhood/adolescence. During infancy from birth to 1 year, physical growth is rapid as infants double and triple their birth weight. Important motor milestones include sitting up, crawling, standing, and walking. Cognitive development involves learning, language acquisition, and social skills. Multiple theories aim to describe growth and development processes across different domains.