Dermal fillers are injectable substances used to plump up and add volume to areas of the face that have lost elasticity and collagen due to aging. They can smooth wrinkles, fill in deep creases, enhance shallow contours, and improve the appearance of scars. Common substances used in dermal fillers include hyaluronic acid, calcium hydroxylapatite, and poly-L-lactic acid. Dermal fillers are minimally invasive and typically provide immediate results with minimal downtime, though they are temporary and require periodic touch-ups for sustained effects.