Man passes through several stages of development from pre-natal to old age. These stages include infancy, childhood, puberty, adolescence, adulthood, middle age, and old age. Each stage has developmental tasks such as learning to walk and talk in infancy, mastering reading and writing skills in childhood, and earning a living and starting a family in adulthood. Individuals may progress through these stages at different rates due to hereditary and environmental factors. Teachers, parents, and society should be aware of differences in individual development and not expect all children to develop skills at the same pace.