These are natural or synthetic chemicals used to prevent water loss (drying) of the skin. The natural herbal or vegetable oils are better absorbed by the skin. The synthetic oils are usually allergans, and, when absorbed into the body, introduce a synthetic substance into a natural environment.

Emollient (Wikipedia)

A moisturizer, or emollient, is a cosmetic preparation used for protecting, moisturizing, and lubricating the skin. These functions are normally performed by sebum produced by healthy skin. The word "emollient" is derived from the Latin verb mollire, to soften.

White petrolatum