What is a lip liner?
A lip liner, a lip pencil, is a product used to define and shape your lips. Lipliner is to lipstick what a base coat is to nail polish. It is not crucial, but it does make your lipstick look better and last longer.
So lip liners act as primers to boost the color and longevity of your lipstick. The formula of a lip liner helps your lipstick adhere better to your lips without bleeding.
You can also use a lip liner to correct thin or uneven lips. If you have thin lips, applying lipstick correctly cannot be easy. You can use a lip pencil to outline your lips to add more volume to the actual shape of your lips.