Growth factors are one of those often-buzzed about ingredients that are on the tip of everyone’s tongue—and on the packaging of many bottles—but still have some mystery surrounding them. What are they, exactly, and where do they come from? More importantly, what can they actually do for your skin? “Growth factors are naturally-occuring substances that regulate various cellular processes, including growth, proliferation, and differentiation. They are crucial for tissue development, wound healing, and maintaining the overall health and function of cells,” explains Robyn Gmyrek, MD, a board-certified dermatologist in New York City. (It also bears mentioning that they can be derived from either human cells or plants.) “When applied topically, growth factor serums may help support collagen production, improve skin elasticity, enhance the skin’s natural repair processes, and minimize the appearance of fine lines and wrinkles. They can also contribute to hydration and overall skin rejuvenation,” Gmyrek explains. Long story short, they’re a great anti-aging ingredient, targeting a variety of the things that can make us look older than we are. Their other big boon: Unlike other anti-aging ingredients (retinoids, we’re looking at you), growth factors are typically very well-tolerated and unlikely to cause irritation.