Nails can have a variety of diseases, including nail plate deformation and deformity, nail discoloration, subnail hemorrhage, ingrown nails, periungual inflammation and subnail tumors and other nail diseases. 1. Nail plate deformation and deformity: it can be congenital abnormality or caused by systemic diseases, skin diseases, etc. Nail hypertrophy, giant nail, nail curvature, nail atrophy, soft nail, anti-nail, nail longitudinal cleft, nail transverse grooves, nail splitting, nail separation, or nail loss, etc. Nail deformity can be caused by a variety of diseases such as nail discoloration, nail discoloration, nail bleeding, ingrown nails, peri-nail inflammation and sub-nail tumor. 2. Nail discoloration: nail plate can be discolored due to various reasons, such as severe anemia, jaundice, nail groove inflammation, nail nevus and other diseases can cause yellow nail, white nail, black nail, green nail, green nail or nail discoloration manifestations such as half nail. 3. Bleeding under the nail: the end of finger or toe is hit or squeezed, which can cause severe pain and bleeding under the nail. 4. Embedded nail: It refers to the condition in which the lateral edge of the nail is embedded in the soft tissues around the nail, causing pressure pain or infection. 5. Inflammation around the nail: bacterial infection or trauma can make the nail bed inflamed, pus, forming nail bed inflammation; puncture, scratches and other factors can cause onychomycosis. 6. Tumor under the nail: benign or malignant tumors can occur under the nail, benign tumors such as exophytic bone warts under the nail, pigmented nevus under the nail, pyogenic granuloma, etc., malignant tumors such as Bowen’s disease, melanoma and so on. If the nails appear abnormal manifestations, we should consult a doctor in time to make a clear diagnosis.