Quick Answer: Sunscreen, also known as sunblock, sun lotion or sun cream, is a photoprotective topical product for the skin that helps protect against sunburn and prevent skin cancer. Sunscreens come as lotions, sprays, gels, foams, sticks, powders and other topical products. Sunscreens are common supplements to clothing, particularly sunglasses, sunhats and special sun protective clothing, and other forms of photoprotection. Sunscreen is on the World Health Organization's List of Essential Medicines. Sunscreen products may be classified according to the type of active ingredient present in the formulation as: • Mineral sunscreens, which use only inorganic compounds as active ingredients. These ingredients primarily work by absorbing UV rays, with some reflection and scattering of UV radiation also occurring. • Chemical sunscreens, which use organic molecules as active ingredients. Chemical sunscreen ingredients work by absorbing the UV rays and releasing the heat.