Please give me a simple answer of What is mensturatin. i can't understand .

In females, ovary releases one egg every month. The uterus also prepares itself every month to receive to receive a fertilized egg. The inner uterus lining (endometrium) becomes thick and is supplied with blood to nourish the embryo. If the egg is not fertilized, then the uterus lining is not required. Hence, it breaks down and is released in the form of blood and mucus through the vagina. This process lasts for 2-8 days. This cycle occurs every month and is known as menstruation.