Birthmark: A persistent visible mark on the skin that is evident at birth or shortly thereafter. A birthmark is often due to a nevus (a mole) or an hemangioma (a localized collection of small blood vessels).
Birthmarks that are pink or red are commonly capillary hemangiomas -- collections of tiny blood vessels -- that are most evident when the baby cries. Common locations are on the midforehead, the eyelids, just above the nose, between the nose and the upper lip, and the so-called "stork bite" on the nape of the neck. These marks generally become harder to see or disappear entirely within a few years.