Rinse aid actually doesn't have anything to do with rinsing your dishes. Instead, it helps remove water from flatware, plates, bowls, and glasses. Really, it's more of a drying aid, but that just doesn't have the same ring to it.Rinse aid entered the list of products that we’re supposed to be using to keep things clean. Oh, the shame of water spots on our glassware! 

Rinse aid is a surfactant that reduces the surface tension of water. Surface tension is the “skin” effect on a droplet that makes it ball up rather than spread out on a surface. (Think of droplets of water on a leaf.) As a surfactant, rinse aid prevents water from forming into droplets and instead encourages it to drain from the surface in thin sheets. Thus, spots from dissolved minerals left behind from evaporated droplets are diminished.