Your period, officially called menstruation, is the monthly discharge of blood and tissue from your uterus that exits your body through the vaginal opening. Getting your first period is an exciting moment in the transition from girl to woman. And it’s one of the truly unique things about being a woman.

Having a period is a natural part of puberty and is evidence that you are maturing. While the process of puberty will start between the ages of about 8 and 14, most girls menstruate between the ages of 9 and 16. Menstruation is an important part of the reproductive process. It allows women to have babies when they’re grown up and ready.

Getting to know the female reproductive system will help you understand your period better. Use this diagram to see how it all works together.

    What’s on the inside:

  • ovaries (OH-vuhr-ees)
    two reproductive glands that produce hormones and eggs
  • fallopian (fuh-LOH-pee-uhn) tubes
    two tubes through which the egg travels from the ovary to the uterus
  • uterus (YOOT-er-uhs)
    muscular organ in the body where a fertilized egg develops
  • endometrium (en-doh-MEET-ree-um)
    the lining of the uterus that is shed every month
  • cervix (SER-viks)
    the lower part of the uterus
  • vagina (vuh-JY-nuh)
    the canal that leads from the cervix to the outside of the body and through which menstrual fluid passes; when a baby is born, it also passes through the vagina

    What’s on the outside:

  • vulva (VUHL-vuh)
    name of the whole pubic area, containing your external genitalia (outer genitals)
  • pubic bone
    a roundish bone at the top of the genital area
  • mons
    the fatty tissue that covers the pubic bone
  • labia majora (LAY-bee-uh mah-JOHR-uh)
    soft flaps of skin just below the mons; protection for the vagina
  • labia minora (LAY-bee-uh muh-NOR-uh)
    softer lips found inside the outer lips
  • urethra (yoo-REE-thruh)
    small opening found around the middle of the vulva; tube through which urine passes through the body
  • vaginal (VA-jih-nuhl) opening
    the pathway in and out of your reproductive system; larger opening below the urethra
  • hymen (HI-muhn)
    a thin membrane that may partially cover the vaginal opening
  • clitoris (CLIT-or-is)
    an organ of female sexual responsiveness, filled with nerve endings