Hyaluronic Acid, also known as hyaluronan, is a natural compound and important constituent of joint fluid which is found in high concentrations in the eyes, skin, and cartilage. Its main role in the body is to retain water which allows the tissues it's present in to remain well lubricated. Hyaluronic Acid is often taken as a supplement both to support joint health and lubrication as well as to promote skin and hair health.