If there’s one “trendy” skin-care ingredient that comes with benefits that actually deserve your time, it might be hyaluronic acid. Skin-care bloggers and dermatologists alike frequently recommend that nearly everyone incorporate hyaluronic acid into their routines frequently for good reason: It apparently has some intensely hydrating effects.

So what actually is in this magical substance? And what’s the best way to use it? We spoke to a few experts to find out.