The period during which boys and girls reach sexual maturity and become capable of reproduction is known as puberty. The onset of puberty is marked with several changes in the human body. In males, when the onset of puberty begins, the following characteristics are developed: deepening of the voice, facial hair growth, rapid increase in height etc.

The menstrual cycle can be characterised as the regular natural change that occurs in the female reproductive system. The cycle is required for the production of oocytes, and for the preparation of the uterus for pregnancy. The four phases of the menstrual cycle are menstruation, the follicular phase, ovulation, and the luteal phase. If fertilisation does not occur, the released egg and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in women which is called menstruation. The stoppage of menstruation is termed menopause.