“Birthmark” is a common name, as the name implies, is a mark brought by the fetus, generally divided into two kinds of red (vascular) birthmarks and pigmented birthmarks. The real birthmark is called “Mongolian spot”, which is cyanotic in color and located in the lumbar-sacral area, and usually fades naturally without treatment. Hemangiomas are mostly located on the head and face, and they develop rapidly within one year of age. If the best time for treatment is delayed, they may cause disfigurement or disability, so they should be treated promptly after birth. Coffee spots and nevus of Ota obviously affect the facial appearance and should be actively treated after the age of 1 year. Giant nevi with large area and hair on the surface, black hair nevi or small nevi located in areas prone to friction should be treated promptly because they have the tendency to become malignant.