Development is a dynamic process starting from prenatal period and lasting for life. In order to understand development, some basic concepts such as development, growth, progress, change, maturation, learning, readiness, period, critical period, time, and historical time should be mentioned. To understand development, it is necessary to know the principle of development. Development is affected by biological and many environmental factors. It is accepted that development is a product of heredity and environment. The periods of development, which take part in the life of the individual and defined with certain characteristics, are classified as prenatal, infancy, early childhood, middle childhood, adolescence, adulthood, and old age. Development is examined by branching such as physical, motor, cognitive, language, social and emotional, personality, moral, perceptual development, and sexual development. Families and educators play an important role in supporting the development of children. Ethics is a very sensitive issue in child development.