Our skin naturally has a mixture of oils (epidermal lipids) and water to help keep it soft but too much hand washing, a skin disease such as eczema or just normal aging can strip this protection and cause dry, irritated skin -- especially on our hands. The oils in petroleum jelly help to seal in moisture and the thick ointment stays on the surface of the skin longer than water-based lotions, promoting longer healing. Worried about greasy residue? Rub a small amount of jelly onto hands and cuticles until it soaks in and save the slathering for overnight when you can cover your hands with cotton gloves.
It's not just hands and feet that can benefit from emollients. Keep your whole body smooth and supple, next.