Retinol is a precursor to the bioactive form of vitamin A, a molecule which plays an important role within the body. When applied to the skin, retinol is converted to retinoic acid, providing many skin benefits. It has been shown to be an effective ingredient to target signs of aging, which include uneven tone and fine lines & wrinkles. Its skin-smoothing effects are generally associated with its role in supporting collagen content (as this structural protein is responsible for skin firmness) and supporting hyaluronic acid (as the water-binding properties of HA support skin plumpness). It has also been shown to visibly target pigmentation, and aid with the shedding of dead skin, resulting in smoother, more even skin. Retinol use however, is commonly associated with dryness, discomfort and redness when first adjusting to the ingredient. For this reason it is recommended to start at lower concentrations and build up as the skin adapts to the use of retinols.