Your period is one stage of your menstrual cycle which is part of the female reproductive system, ultimately it’s about having children. Although having babies is probably the last thing on your mind right now, that’s exactly what your body is preparing for! When you reach puberty your ovaries will begin to ripen eggs and release these each month which travel down to the uterus (womb). The lining of the uterus thickens so it can provide nutrients for a fertilised egg. If the egg is not fertilised (during sex), the extra lining of the uterus will break down and come out through the vagina – which is your period, ta-da!