Human development refers to the changes that occur across the lifespan from conception through old age. It includes physical, cognitive, social, moral, and spiritual development. Major principles of development include that it proceeds in an orderly pattern from the center of the body outward and from the head downward, though the rate and outcomes vary between individuals. Development is influenced by biological, cognitive, and socio-emotional processes and occurs gradually through both maturation and learning. A life-span approach views development as lifelong and multidimensional rather than concentrated in childhood alone.