The study of the chronological processes or changes that occur from fertilization to the formation of the single-celled eukaryote (zygote) through to the formation of a human in utero and development of the human from birth through puberty to adult.
Human development covers the various stages of human life:
- prenatal – from fertilization to birth
- child – from birth to puberty
- adolescence or puberty
- adult – from age 21 onwards