Development refers to the changes that occur between conception and death, especially those that are orderly and remain for a reasonably long period. These changes result in behavior that is more organized, effective, and complex. Development can be divided into physical, personal, social, and cognitive aspects. It involves changes that occur naturally through maturation and genetic programming, as well as changes brought about through environmental interaction and learning. Modern developmental psychologists believe that both nature and nurture influence development, with biological factors playing a stronger role in some aspects like physical development and environmental factors more influential for other areas such as moral development. Development generally follows predictable stages and later changes build upon earlier ones, though rates and sequences can vary between individuals.