Vasculitis, also known as vasculitis, is a group of disease syndromes associated with inflammatory changes in blood vessels. They are commonly characterized by inflammatory changes in or around the walls of arteries, veins, and microvessels of varying sizes, resulting in narrowing of the lumen, obstruction of circulation, and dysfunction of the involved organs. Clinical manifestations vary depending on the type, size, and location of the involved vessels, the stage of inflammation, and the characteristics of the lesion. Vasculitis can involve large vessels, medium vessels, and small vessels. The most predominant vasculitis of large vessels is giant cell arteritis and great arteritis, medium-sized vasculitis is most commonly associated with polyarteritis nodosa and Kawasaki disease, and small vasculitis is most typically associated with Weyers granulomatosis, allergic granulomatous vasculitis, microscopic polyangiitis, allergic purpura, primary cryoglobulinemia, and cutaneous leukocyte fragmentation vasculitis. The etiology of vasculitis is not fully understood and varies among vasculitic diseases. Deposition of immune complexes in the vessel wall is one of the causes. Treatment options for vasculitis are significantly correlated with the site of involvement, and even for the same disease, the therapeutic drugs and treatment options are not identical depending on the organ involved. Immunosuppressive therapy is commonly used, and the main therapeutic regimen is a combination of glucocorticoids and cytotoxic drugs or alone.