As a woman, do you know your own body? Do you know what “period” is all about? Do you know what a normal period looks like? “Periods, also known as menstruation, are the cyclical shedding of the endometrium of the uterus. Each month, as the follicles continue to develop, the lining of the uterus grows. The endometrium grows to its optimal size during ovulation, ready for the fertilized egg to be laid. If the sperm and egg successfully unite to become a fertilized egg and “take root” in the uterine cavity, the endometrium will become more “fertile” to supply nutrients and nurture life. If there is no conception, the endometrium will be shed about 14 days after ovulation and the “period” will come. So, menstruation is actually the “inner bleeding” of the uterus because the egg is not fertilized. This is the mystery of the origin of menstruation. What should a normal period look like? First, there is a regularity in timing. A woman’s life can be divided into seven different biological stages. From the age of 18 to the age of 50, women are sexually mature. The most obvious outward manifestation of this period is regular menstruation. For an individual, the length of the menstrual cycle should be stable and come on time every month. However, for different people, the menstrual cycle varies from 21 days to 35 days. In general, it is normal for the menstrual cycle to be basically fixed, from 21 to 35 days. Secondly, menstruation should be short and moderate in volume. When menstruation occurs, the endometrium is shed in synchronization, along with a small amount of blood and secretions that are discharged through the vagina. The volume of the uterine cavity is usually about 5mL, which is equivalent to the volume of two Coke bottle caps. Therefore, the volume of menstruation is not too much, about 20-80mL. After the endometrium is shed, the endometrium immediately starts to repair and proliferate, and together with the contraction of the uterus, the bleeding can be stopped soon. So the period will not be long, usually about 2-8 days.