Eyeliner is a cosmetic product used to define and enhance the eyes. It comes in various forms, including pencil, liquid, gel, and cream. Eyeliner can be applied along the upper and lower lash lines to create different looks, from subtle to dramatic. Many people use eyeliner to accentuate their eye shape and make their eyes appear larger or more defined. It is available in a wide range of colors, allowing for creative expression. Proper application techniques can vary, and tools like brushes or applicators may be used for precision.