Melanoma is a type of malignant tumor with a relatively high level of malignancy. The exact causes of melanoma are not very clear but may be related to multiple factors including genetics, irritation, viral infection, and immunity. Generally, there are four types of melanoma: nodular melanoma, superficial spreading melanoma, acral lentiginous melanoma, and lentigo maligna melanoma. Once melanoma occurs, it is crucial to seek prompt medical diagnosis and treatment.