Human development focuses on physical, cognitive, social, intellectual, perceptual, personality and emotional growth across the lifespan. There are various developmental stages from conception through old age, each with characteristic changes. The stages include pre-natal development, infancy, early childhood, late childhood, adolescence, early adulthood, middle age, and old age. Understanding these developmental stages and changes across the lifespan allows people to better respond to growth and effectively plan for the future.