A period generally refers to menstruation, which is the phenomenon of endometrial peeling and bleeding that occurs with the cyclical changes of the ovaries and is a very important physiological phenomenon for women. Having regular menstruation means that a woman’s reproductive function is more maturely developed. Ovarian secretion of estrogen causes the endometrium to thicken, and after ovulation the endometrium will become edematous due to the combined effect of estrogen and progesterone. If the egg and sperm combine at this time a fertilized egg will be formed, which will be pregnant when it lays and develops. If the egg is not fertilized, after another 14 days, due to the withdrawal of estrogen and progesterone, the endometrium will become necrotic and shed causing bleeding, resulting in menstruation. The first menstruation is a sign of female puberty and the age of menarche is around 10-17 years old. The menstrual cycle refers to the first day of the current period to the first day of the next period. The normal length of the menstrual cycle is 21-35 days, the menstrual period lasts about 1 week at a time, and the volume of menstrual blood is 30-50 ml. If the menstrual cycle is more than 35 days or less than 21 days, and the menstrual volume is too much or too little, it is abnormal menstruation and should be improved promptly by seeking medical attention. During menstruation, you should pay attention to keep warm and do not get cold or eat cold food. Pay attention to a reasonable diet, eat more protein-rich foods, such as meat, milk, eggs, etc., and do not eat spicy and stimulating foods to avoid menstrual pain. Pay attention to keep the vulva clean and hygienic, do not swim or take a tub bath, etc. Do not overwork, ensure sufficient rest and avoid staying up late. Also prohibit smoking, alcohol and sexual life during menstruation.