Sunscreen agents are used to prevent sunburn. Limiting your exposure to the sun and using sunscreen agents when in the sun may help prevent early wrinkling and skin cancer.

There are two kinds of sunscreen agents: chemical and physical. Chemical sunscreen agents protect you from the sun by absorbing the ultraviolet (UV) and visible sun rays, while physical sunscreen agents reflect, scatter, absorb, or block these rays.

Sunscreen agents often contain more than one ingredient. For example, products may contain one ingredient that provides protection against the ultraviolet A (UVA) sun rays and another ingredient that protects you from the ultraviolet B (UVB) sun rays, which are more likely to cause sunburn than the UVA sun rays. Ideally, coverage should include protection against both UVA and UVB sun rays.

The sun protection factor (SPF) that you find on the label of these products tells you the minimum amount of UVB sunlight that is needed with that product to produce redness on sunscreen-protected skin as compared with unprotected skin. Sunscreen products with high SPFs will provide more protection against the sun.