You may not have heard of homosalate before. Still, if you’re using sunscreen every morning (insert obligatory reminder that daily SPF is a non-negotiable), there’s a good chance that you’re using the ingredient daily without even knowing it. Sunscreens fall into two camps: physical formulas (which rely on minerals such as zinc oxide and titanium dioxide to sit on top of the skin and deflect rays) and chemical formulas (which rely on chemical ingredients that penetrate the skin and absorb UV rays before they can cause damage). Homosalate is the main active in the latter, found in an array of chemical sunscreens.