The causes of baldness can be seen clinically in the following areas: the first is neurogenic alopecia, which is commonly associated with increased hair loss due to excessive mental stress. The second is endocrine alopecia. Hair growth is influenced by a variety of endocrine hormones, so when endocrine abnormalities occur in the body, it can cause hair loss. The most common ones are hirsutism and androgenic alopecia. Third, nutritional alopecia, malnutrition and metabolic disorders of the body can lead to changes in hair quality and color, or even diffuse hair loss. The fourth is physical alopecia, which includes mechanical irritation and exposure to radioactive substances. The fifth is chemical alopecia, where chemical factors can lead to hair color changes and even hair loss. The sixth one is infectious alopecia. Infection by various pathogens is a major factor in hair diseases, including bacteria, viruses, spirochetes, fungi, parasites, etc. The seventh one is congenital and seasonal alopecia, which is also a more common cause in clinical practice.