It is intended to fill in uneven areas on the outer edges of the lips before applying lipstick to give a smoother shape. It is also used to outline the lips, keeping lipstick inside the lip area and preventing it from "bleeding", creating a bigger contrast and making the lips stand out more. Alternatively, lip liner can be used to fill in the entire lip before the application of lipstick, and in some cases is worn as a lipstick on its own. The product is usually sold in a retractable tube or pencil form which can be sharpened. Lip liner is usually available in the same range of colors as lipsticks: e.g., reds, pinks, browns, plums, etc. Lip liner also comes in invisible, for giving the illusion of smooth lips without adding or affecting color.