Skin care used to be simple: Clean hands, wash face, apply moisturizer, the end. Now? Not so much. But just as we’ve collectively become comfortable incorporating essences, toners, serums, oils, masks and more into our routines, a new category of skin care has bubbled to the surface — and it just may be the most confusing one yet. We’re talking about the growing-by-the-second sector of at-home skin-care devices.

Below, we break down exactly what you need to know about each type of tool, including which ones deserve a spot on your bathroom shelf.