A quick debrief: There are three main kinds of moisturizers. The first is humectants, which include hyaluronic acid and glycerin, for example. These moisturizers pull water into the surface of the skin (hence, why you should apply your body lotion to damp skin, so the humectants have an easier time drawing in hydration). Then you have emollients that help soften the skin and make it feel more comfortable by filling in cracks. A few examples include ceramides, shea butter, and certain oils.
The last one, however, is what we’re focusing on today—occlusives. These seal in moisture and act as a water retention barrier (aka, they help prevent TEWL). Traditional occlusives include thick ointments (like petrolatum-based topicals), but botanical oils serve a similar function.