Human development occurs throughout the lifespan, from conception through old age. It includes physical, cognitive, and socio-emotional changes. Development follows general principles - it is relatively orderly, varies between individuals, and takes place gradually through the interaction of biological, cognitive, and social processes. Approaches to development include the traditional view that most occurs by adulthood and the lifespan view that development continues throughout life in a multi-dimensional, plastic, and contextual manner focused on growth, maintenance, and regulation. Principles of child development state that all domains are interrelated, development proceeds at varying rates and is shaped by both nature and nurture through sensitive periods.