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Glossary 

# Sunscreen

SUN-skreen 

## Definition

Sunscreen is a topical product that protects the skin from the harmful effects of ultraviolet (UV) radiation, which causes sunburn, premature aging, hyperpigmentation, and skin cancer. There are two main types: chemical (organic) sunscreens, which absorb UV rays and convert them to heat using ingredients like avobenzone, homosalate, and octisalate; and mineral (physical/inorganic) sunscreens, which sit on the skin's surface and reflect or scatter UV rays using zinc oxide and/or titanium dioxide. Many modern formulations combine both types. Dermatologists consider daily sunscreen use the single most important anti-aging skincare step. For adequate protection, apply a broad-spectrum SPF 30 or higher sunscreen generously (about ¼ teaspoon for the face) 15 minutes before sun exposure and reapply every two hours, or immediately after swimming or sweating. Sunscreen should be the last step in a morning skincare routine and applied before makeup.

## Related Terms

[SPF](/glossary/spf)[Broad Spectrum](/glossary/broad-spectrum)[UVA](/glossary/uva)[UVB](/glossary/uvb)[Zinc Oxide](/glossary/zinc-oxide)

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[Salicylic Acid](/glossary/salicylic-acid)[Sebaceous Gland](/glossary/sebaceous-gland)[Sebum](/glossary/sebum)[Sensitized Skin](/glossary/sensitized-skin)[Skin Cycling](/glossary/skin-cycling)[SPF](/glossary/spf)

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