The stages of human development can be simplified as follows:
- Prenatal Stage: Includes the germinal, embryonic, and fetal periods.
- Neonatal and Infancy Stage: Neonatal (first 2-4 weeks) and infancy (up to 2 years) are usually considered together.
- Early Childhood: Ages 2 to 6.
- Middle Childhood: Ages 6 to around 12 (beginning of puberty).
- Adolescence: Ages 12 to 18 (puberty to adulthood).