In psychology, Human development is the study of mental and related processes across the life span. In this subfield of psychology is concerned with the changes everyone goes through from birth to death. Human development is one of the largest and most complex specialties in the behavioral sciences.

Although we grow up to be unique individuals, a great deal of our development is similar and predictable, and occurs according to certain relatively fixed schedules; for example, puberty, adolescents, etc. Also including the most influential areas of research in developmental psychology are the processes of attachment or bonding between infant and mother, the development of intellectual abilities, and the changes relating to the again process.

The sweeping discoveries of Jean Piaget formed the entire foundations of what we know today about cognitive development. Piaget had devoted 50 years of his life to studying intellectual development in children. His work led to his famous theory of cognitive development. Piaget has four stages of cognitive development in human development. The stages are sensori-motor which covers children from age 0 until 2, the preoperational stage which covers children ages 2 until 7, the concrete operations is for ages 7 until 11, and formal operations for ages 11 and up. Another important developmental psychologist, Harry Harlow, made a lot of contributions to the study of human development since Sigmund Freud. He studied on how early life experiences affected our adulthood. Harlow performed an experiment with monkeys to see whether the monkeys would be in better health in the hands of humans in a laboratory or with their own mothers. Harlow and his people noticed that the monkeys became attached to the cloth pads that were placed on the bottom of their cages. They started showing this sort of attachment as early as one day old. Harlow and his people theorized that there must be some basic need in these infant monkeys for close contact with something soft and comforting in addition to primary biological needs such as hunger and thirst.

 University departments with this name study human development from a psychological perspective as opposed to studying biological human development exclusively. Historically, many such departments expanded from their original subject matter, Child development. Majoring in Human Development programs in college can lead to a career in various Human Services. Those with a degree in Human Development have found work in the fields of social work, child care, education, elderly care and counseling. Main article: Developmental psychology, which is roughly synonymous. But we can also include in it our prenatal period very strongly because it is actual developmental phase of brain, what we get in our later age all this depend on our development of our brain.