Retinol is a pure form of vitamin a and a type of retinoid. Retinoids are needed for a large number of processes in the body. Retinol stimulates collagen production and cell renewal and has been clinically proven to improve the appearance wrinkles, skin discolouration and blemishes. When applied to the skin, retinol converts to retinal (retinoic acid). Retinoids can cause irritation; whereas retinol has been found to produce results with less irritation and is often considered a more tolerable form of vitamin A.