Common skin cancers are as follows: 1. Basal cell carcinoma: it is a low-grade malignant skin tumor, which usually can be removed in situ and usually does not metastasize; 2. Squamous cell carcinoma: it is easy to occur in the exposed area and is more malignant than basal cell carcinoma, which needs to be surgically removed when found; 3. Malignant melanoma: it is most likely to occur at the extremity, such as irregular pigmented nevus at the extremity, which should be treated as early as possible off. The malignancy of malignant melanoma is higher than that of basal cell carcinoma and squamous cell carcinoma.