Glycolic acid (or hydroxyacetic) is the smallest AHA acid. It is a colourless, odourless, and hygroscopic crystal substance highly soluble in water. It is used in various skin care products and is obtained from plants and other natural sources such as fruit, sugar cane, and milk. A great advantage of this acid is that it has the smallest molecule size of all other AHA acids, which means that the skin absorbs it very easily. It is contained in all types of cosmetic products such as facial cleansers, tonics, or scrubs and is most often used as a chemical scrub, thus stimulating cell renewal. It increases the production of collagen and hyaluronic acid, thereby reducing the appearance of fine lines and wrinkles on the face. Products that lighten the skin and even out the complexion contain glycolic acid as the main ingredient. It is most effective when used on normal, combination and oily skin.