Filler

I use it like a primer. You can't rub this stuff in like a moisturizer because that's not what it's for. You have to just gently smooth it over you skin and it acts a bit like a filler and reflects the light in such a way that fine lines look reduced. If you aren't sure go to a place that lets you try it and just sweep it over your palm. You'll see immediately that the lines on that palm look far more reduced and blurred compared to the other one. I find it a little pricey for a primer but it does do what it says.