Among the many categories of advanced wound dressing products available today, hydrogels are popular because they are effective, comfortable, easy to use, and cost effective. With proper use, these agents provide control of wound surface hydration, sometimes absorbing excess exudate and often providing moisture. This review describes the chemistry of hydrogels, the physiology of their interaction with the wound surface, and their role in patient care. Hydrogels have been proven effective in facilitating repair of pressure, diabetic, vascular, burn, and other wounds, and they have supplanted saline-moistened gauze for many applications. Clinical evidence suggests that no particular hydrogel is significantly more efficacious than any other, implying that other factors such as cost and ease of use may guide clinician choice of product within this class of wound dressings.