The skin is the largest organ of the human body. It serves various functions, directly interacts with physical, chemical, and biological agents from the external environment. These agents can cause numerous skin diseases. Of these, the relationship between ultraviolet (UV) rays and skin cancer has been proved.

UV radiations act on tumor suppression genes and/or tumor proliferation genes, altering the activity of these genes and leading to a loss of cell proliferation control and the formation of tumors. 

UVB causes mutations that change C to T or CC to TT, accounting for the majority of mutations causing squamous cell carcinoma (SCC). UVA causes mutations through the generation of the main oxidant radicals, where OH- radicals cause G to T. 

Sunscreen consists of inorganic and organic substances that, when applied to the skin, reduce the intensity of ultraviolet rays and possibly visible light rays reaching the stratum corneum of the skin.