There are more than 15 types of skin cancer that affect the human body. In general though, it's best to think of them as melanomas and non-melanomas. Melanomas account for only 4.0% of the skin cancers that humans get, but they form 73% of the mortality. So it's very serious.
Non-melanoma skin cancers can include basal cell carcinoma, squamous cell carcinoma, Merkel cell carcinoma and other rare types. Non-melanoma skin cancers are actually more associated with sun exposure than melanoma. When you think of non-melanoma skin cancers, it's important to know that the majority of them do not metastasize, which is very good.
So if you notice a bump, it can be easily treated with an excision, without necessitating chemotherapy or radiation therapy. Unlike melanoma, when if it's metastasized to the rest of the body, will require many types of treatment and will require an oncologist, a dermatologist, and oftentimes a radiation oncologist to work together.