Two vascular birthmarks are hemangiomas and vascular malformations. Hemangiomas grow by cellular proliferation. Their hallmark is rapid neonatal growth. Spontaneous regression begins when the infant is 6 to 10 months old, but it may continue until 8 to 10 years of age. Hemangiomas are infrequently life-threatening. Pharmacologic treatment is indispensible; unsightly sequelae require surgical treatment. Vascular malformations consist of dysplastic vessels and are present on a lifelong basis. They are either slow-flow (capillary, venous, lymphatic) or fast-flow anomalies with arteriovenous shunting. Complex combined vascular malformations are observed as well. Ten years ago angiographic studies clearly demonstrated the differences among the various lesions. Today a noninvasive diagnostic approach is recommended, particularly in children. Ultrasonography, Doppler flow imaging, and magnetic resonance imaging are the most informative techniques, revealing the extent of tissue involvement and differentiating fast-flow from slow-flow anomalies. Risks and management differ depending on the type of vascular malformation.