You know moisturizers come in many forms (lotions, creams, gels, and balms, to name a few), but they all fall into three basic types, explains Ron Robinson, a cosmetic chemist in NYC and founder of

Likely the first kind of moisturizer you ever used (think diaper balm), these create a barrier so moisture can't escape. (It's like shrink-wrapping a muffin so it stays moist.) What you'll see on the label: petrolatum, dimethicone, lanolin, mineral oil

These softeners smooth your skin by preventing moisture loss from cells. What you'll see on the label: keratin, ceramides, stearyl alcohol

This type of super-moisturizer acts like a sponge, attracting water from deeper layers of skin into the top layer to boost moisture. What you'll see on the label: hyaluronic acid, glycerin