Human development is the process of growth to maturity. The process begins with fertilisation, where an egg released from the ovary of a female is penetrated by sperm.  The egg then lodges in the uterus, where an embryo and later fetus develop until birth. Growth and development occur after birth and include both physical and psychological development, influenced by genetic, hormonal, environmental and other factors.  Development and growth continue throughout life, through childhood, adolescence, and through adulthood to senility, and are referred to as the process of ageing.  The entire process can be divided into distinctive phases as follows :  1. Fertilization of gametes. 2. Embryonic development. 3. Fetal development 4. Infant 5. Childhood 6. Puberty  7. Adulthood 8. Old Age.