Lips are an important feature of facial aesthetics.
Thin lips are commonly regarded as masculine. However, this is a misconception because males actually don't have thinner lips than females. Males have larger skulls which makes their lips appear thinner. A long chin makes the lips appear thinner as well.
Females have lips that are more plump (anterior projection). Plump lips advertise youth because lips get thinner with age.
Blacks have genetically thicker lips. Thick lips are useful in chewing hard foods because they protect the lips from being damaged.
Lips should have a pronounced vermilion border. A pronounced vermilion border indicates lack of orbicularis oris hypertrophy. A correct swallowing pattern helps to prevent this hypertrophy.