Inorganic sunscreens work by physically reflecting or scattering ultraviolet rays away from the skin. These are mineral-based formulas that include titanium dioxide and zinc oxide. Physical sunscreens do not deteriorate when exposed to light, usually do not irritate skin and provide a matte look. They also start working as soon as they are applied. These may be the best choice for oily or sensitive skin.
Organic sunscreens work by absorbing UV rays before they reach the skin. Key ingredients include octocrylene, homosalate, avobenzone (Parsol 1789) and Mexoryl. Chemical filters tend to provide better protection against UVA (aging) rays, which is ideal for anti-aging, but should be applied 20 minutes before sun exposure to maximize effectiveness.
Regardless of which category you opt for, remember, not all sunscreens are created equal. For best results, check the label before you lather up, making sure any sunscreen product you apply offers broad spectrum UVA and UVB coverage.