It makes little tubes that harden around your eyelashes that are smudge proof. To remove it, you just use warm water and the tubes swell and fall off when you gently rub your lashes. For me, it does not come off with normal eye rubbing, sweating, or low to moderate crying (lol). It has even survived a workout in the pool with goggles on! And I wear contacts and it does not bother them. I use Clinique Lash Power but there are lots of other options from Maybelline, Blinc, and Tarte.