Hyaluronic acid has been used in medicine for decades to treat skin, wounds, and scars, as a joint lubricant for osteoarthritis, and for dry eyes. It is found in high concentrations in tissues with a particularly high need for moisture. As we age, the natural production of hyaluronic acid in the body decreases, leading to sagging skin, the formation of fine lines, dry eyes, and joint discomfort. However, hyaluronic acid can be used strategically to counteract the aging process. This guide describes the modern applications in both cosmetic treatments and osteoarthritis therapy. The reader will learn about the diverse functions that hyaluronic acid performs in the body and how it should be used to unleash its healing effects.