Puberty, period in the human life span during which the organs of sexual reproduction mature. This maturation is evidenced in females by the onset of menstruation, in males by the production of semen, and in both by the enlargement of the external genitalia. Rapid growth marks a range of physiological changes. Various secondary sexual characteristics also appear for the first time during puberty; in males, production of body hair increases markedly, particularly in the pubic, axillary, and facial regions, and the voice usually changes and becomes deeper in tone; in females, hair also appears in the pubic and axillary regions, and the breasts become enlarged. Accelerated development of the sweat glands in both sexes may trigger acne.

Puberty usually occurs in males between the ages of 13 and 16, and in females between the ages of 11 and 14. Among the pathological conditions related to puberty are amenorrhea and pubertas praecox. The former is characterized by an absence or cessation of menstrual flow not caused by pregnancy. The latter is the premature appearance in the male or female of the typical physiological characteristics of puberty and is caused by disturbances of secretion in the anterior pituitary, in the adrenals, or in the gonads.