Vegetable glycerin is a naturally occurring by product of soap making. As a moisturizing ingredient, glycerin helps the skin to attract and retain its own natural moisture, leaving it feeling soft.
Rather than sitting on top of the skin, glycerin softens the skin while permitting it to breathe. Vegetable glycerin can be added to creams, lotions, bath salts etc to help moisturize the skin.
Vegetable glycerin is a humectant and attracts moisture, so use in moderation.