Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Skin Cancer ?
    ### Response:
    Skin cancer occurs when cancer cells form in the tissues of the skin. The skin is mainly made up of two layers: the inner layer, called the dermis, and the outer layer, called the epidermis. Within the epidermis, there are three types of cells; squamous cells, basal cells, and melanocytes.
    