Puberty normally follows a sequence of events which makes staging possible

Tanner staging for pubic hair

Both sexes:

1. Pre-pubertal: no pubic hair
2. Some downy hair at the base of the penis in males or over the labia majora in females
3. Coarser, thicker and curlier hair that spreads laterally to cover more of the pubis
4. Adult hair, not spreading to the thighs
5. Adult hair, spread to the medial thighs

Tanner staging for females

Breast changes:

1. Prepubertal
2. Breast bud
3. Juvenile with smooth contour
4. Areola and papilla project above breast
5. Adult contour

Tanner staging for males

Male genital changes: