Sunscreen (also commonly known as sunblock, sun tan lotion, sun screen, sunburn cream or block out) is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet (UV) radiation on the skin exposed to sunlight and thus helps protect against sunburn. Skin-lightening products have sunscreen to protect lightened skin because light skin is more susceptible to sun damage than darker skin. A number of sunscreens have tanning powder to help the skin to darken or tan; however, tanning powder does not provide protection from UV rays.

Sunscreens contain one or more of the following ingredients:

Depending on the mode of action sunscreens can be classified into physical sunscreens (i.e., those that reflect the sunlight) or chemical sunscreens (i.e., those that absorb the UV light).

Medical organizations such as the American Cancer Society recommend the use of sunscreen because it aids in the prevention of developing squamous cell carcinomas and basal-cell carcinomas. However, the use of sunscreens is controversial for various reasons. Many sunscreens do not block UVA radiation, which does not cause sunburn but can increase the rate of melanoma, another kind of skin cancer, and photodermatitis, so people using sunscreens may be exposed to high UVA levels without realizing it. The use of broad-spectrum (UVA/UVB) sunscreens can address this concern.