Before the 1980s, the understanding of vascular diseases was rather vague and lacked scientific and uniform classification standards. In 1982, Professor Mulliken of the Department of Plastic Surgery at Harvard University Boston Children’s Hospital proposed a classification based on the biological properties of vascular endothelial cells, dividing vascular diseases into hemangiomas and vascular malformations, believing that the fundamental difference between the two was the presence or absence of abnormal proliferation of vascular endothelial cells, which became the basis of modern classification standards. The International Society for the Study of Vascular Anomalies (ISSVA) was founded in 1992 in Budapest, Hungary. At its 1996 congress, the ISSVA developed a more complete classification system that has gained widespread acceptance and has become a common language for researchers from different disciplines worldwide. In this classification system, vascular lesions are divided into vascular tumors and vascular malformations. Among them, vascular malformations are subdivided into low-flow and high-flow vascular malformations, depending on the hemodynamic differences. The most common types are: ① Infantile Hemangioma: formerly known as strawberry hemangioma, it is the most common benign tumor in infants and children, with a characteristic natural history of rapid proliferation at birth or shortly after birth and spontaneous regression starting around one year of age. The typical presentation is a bright red raised mass, but the skin on the surface of some deep hemangiomas is almost completely normal. Port Wine Stain: It is also known as a bright red nevus and red birthmark, and is a congenital capillary malformation that appears as a pink to purplish-red, well-defined patch, and lesions located on the head and face often appear thickened and nodular in adulthood. Venous Malformation: old name is spongy hemangioma, formed by the expansion and filling of thin-walled veins that communicate abnormally, manifested as a soft purple-blue mass with a sense of compression, the size of which can change with body position. Arteriovenous Malformation: Older known as trapezoid hemangioma, it is a tortuous and dilated mass of blood vessels formed by direct communication between arteries and veins, with high skin temperature and significant pulsation or tremor. Serious complications, such as tissue necrosis, massive bleeding or congestive heart failure, can occur, making it the most harmful type with the highest treatment risk. Lymphatic Malformation: Formerly known as lymphoma, it consists of abnormally dilated lymphatic tracts with clear yellowish lymphatic fluid visible by percutaneous puncture. Depending on the size of the cystic cavity, it can be divided into macrocystic type and microcystic type, which are closely related to the treatment effect. In addition to the above five types, some other types are also relatively common in clinical practice, such as ① Congenital Hemangiomas: Rapid Involuting Congenital Hemangiomas (RICH) and Non-Involuting Congenital Hemangiomas (NICH). Congenital Hemangiomas (NICH). They present with obvious lesions at birth and almost completely regress or do not regress around one year of age, and their appearance, pathology and imaging manifestations are significantly different from those of infantile hemangiomas. Kaposiform Hemangioendothelioma (KHE) and Tufted Angioma (TA): associated with Kasabach-Merritt syndrome, see “Syndromes associated with hemangiomas and vascular malformations” later in this article. “. (iii) Pyogenic Granuloma: Also known as lobulated capillary hemangioma, there are no pathologic inflammatory changes or granuloma-like features. It is more likely to appear after minor local trauma or during pregnancy and appears as a bright red soft raised nodule, usually no more than 2 cm. If ulcers appear on the surface, it is very likely to bleed after touching and has the possibility of recurrence after surgery. Angiokeratoma: It is a purple-red plaque with keratinized surface mainly located at the extremities, confined to the superficial dermis without deep tissue invasion, and can be divided into five types depending on the location and extent of the lesion. Glomuvenous malformation (GM): formerly known as angiosarcoma, named for the presence of spherical cells in the wall of the malformed vein, may be both vascular malformation and tumor in nature. Isolated lesions are mainly found in the nail bed, but may also be located in the extremities, head and neck. They vary in size from a few millimeters to several centimeters and are characterized by marked tenderness or paroxysmal pain. Multiple lesions are autosomal dominant. Most vascular lesions can be diagnosed based on a typical history and clinical presentation, but some must be determined by imaging or histopathological methods. The significance of a clear classification is to unify the understanding of the nature of the lesion and to serve as an important basis for the correct choice of treatment.