Hyaluronic acid is a sugar molecule that occurs naturally in the skin and helps to bind water to collagen, trapping it in the skin, so that skin can appear plumper, dewier, and more hydrated. The collagen in our dermis forms the structure of the skin. Natural hyaluronic acid is bound to collagen on one side and links to water molecules on the other, giving skin its plumpness. As we age, we naturally lose collagen and hyaluronic acid, so the skin becomes dehydrated more quickly. That's why hyaluronic acid can be extra beneficial.