Filler refers to substances used in cosmetic procedures to enhance facial features, reduce wrinkles, or add volume to areas like the lips and cheeks. Common types of fillers include hyaluronic acid, collagen, and calcium hydroxylapatite. These materials are injected into the skin to create a smoother, more youthful appearance. In addition to cosmetic uses, fillers can also be found in various industries, such as food and pharmaceuticals, where they serve to improve texture, stability, or volume. Examples include starch in processed foods and lactose in medications, which help achieve desired product characteristics.