Fillers are injectable substances used to restore volume, plump the skin, and diminish the appearance of wrinkles or fine lines. They typically consist of hyaluronic acid or other materials that add volume to areas of the face, such as lips, cheeks, or around the mouth. This non-invasive cosmetic procedure aims to enhance facial contours, smoothen lines, and revitalize the skin, providing a more youthful and rejuvenated appearance.