Child (birth to 18 years)

Baby (birth to 3 years)

Preteen (9 to 13 years)

Teenager (13 to 18 years)

Adult (18 years till death)

Young adult (18 to 40 years)

Middle age (40 to 60 years)

Old age (60 years till death)

All figures above are approximate. Definitions come from, but are slightly modified from, the English Wikipedia articles on the development of the human body.