Liquid paraffin is a very commonly used moisturizing ingredient, and can be found in many different types of moisturizer. It is also sometimes referred to as white mineral oil.
It is what is called an emollient; basically an ingredient that promotes skin hydration and suppleness. Emollients help to smooth out and support the skin’s barrier by forming a film on top of the skin, thereby, increasing moisture retention within the skin and preventing water loss.