The skin may be the most unique organ in the human body, and the skin on your lips is pretty unique in and of itself.
Most of the skin on your face has around 16 opaque layers of cells, both dead and alive. Your lips, on the other hand, have just three layers of skin and are actually translucent. The lips get their characteristic reddish color from the subsurface layer, the mucous membrane (which also gives lips their pout). The capillaries packed into the mucous membrane layer of your lips push close to the skin on the surface of your lips, revealing the blood within [source: Lip Augmentation]. Push your lips tight together in a mirror and then release the pressure. They go from a light skin color back to red again as the blood returns to the capillaries.
Your lips are among the most expressive parts of your body. Thin, drawn lips display sternness. Lips pulled up into a smile show happiness and warmth. Biting your lip is coy and playful.
You may want to be careful with using that last expression too much. Lip biting contributes to dry, cracked lips -- an expressiveness you want to avoid. Dry lips aren't nearly as attractive as moist, healthy lips. They can also be painful. So, aside from not biting your lips, what are some other ways to prevent dry lips?