The presence of nails is very important, for example, to protect the distal ends of the fingers and toes from damage and also to help the fingers perform fine manipulation. Although finger and toe nails are inanimate and do not bleed or feel pain if you accidentally cut into them with a knife, they can also become diseased. Changes in the texture and structure of the nail and lesions around the nail and nail bed can all be classified as nail disease. The most common are white spots on the nail plate, unevenness, black or red or white streaks, thickening, brittle texture, loss of nail plate destruction, separation of the nail plate from the nail bed, redness and swelling around the nail, darkening, etc. There are various causes of nail disease, summarized as follows: 1. Trauma: For example, if you wear improper shoes, or often climb mountains or play ball, some people’s big toe nails will have black and red spots or white horizontal stripes. There are also female friends often trim nail, can also damage the nail mother, so that the nail plate is not flat. 2.Chemical irritation: Frequent contact with detergents may lead to roughness of the nail plate, separation of the distal end of the nail plate and the nail bed. 3.Tumor: The most common one is perineal fibroma, which is a benign tumor that can compress the nail plate and cause the nail plate to form a longitudinal depression and local roughness. Of course, special attention needs to be paid to malignant tumors in this area, such as squamous cell carcinoma, basal cell carcinoma, malignant melanoma, etc. Particular attention needs to be paid to malignant melanoma, which can be life-threatening if delayed. The early manifestation of malignant melanoma may be black streaks on the nail plate, which will gradually widen over the years and eventually lead to the destruction of the nail plate and the birth of visible tumors on the nail bed and perineum. 4.Other skin diseases: for example, eczema, psoriasis, baldness, lichen planus, follicular keratosis, etc., can lead to changes in the nail plate. 5. Infections: Fungal infections are the most common and lead to “gray nails”. Bacterial infections often show greenish nail plates. 6. Systemic diseases or drugs: high fever, malnutrition, chemotherapy drugs, etc. Changes in the direction of nail growth can also cause problems. It often involves the toenail. Commonly, there are ingrown nails, which are the tips of the lateral edges of the nail plate growing into the skin around it, leading to recurrent local skin infections and pain. There are also pincer nails, where the lateral edge of the nail grows out and bends downward, pressing on the skin tissue and causing pain. The nail disease can be treated, but the main thing is to clarify the diagnosis and the cause, and treat the cause.