Arteriosclerosis is the most common and most important among a group of vascular diseases called arteriosclerosis. The common characteristics of various arteriosclerosis include thickening, hardening, loss of elasticity, and narrowing of the arterial walls. The characteristic of arteriosclerosis is that the affected arterial lesions start from the intima, with various lesions coexisting, including local accumulation of papyraceous and complex carbohydrates, proliferation of fibrous tissue, and formation of plaques due to calcification, along with gradual degradation of the arterial media. Secondary lesions include intraplaque hemorrhage, plaque rupture, and local thrombosis formation. Modern cellular and molecular biology techniques show that arteriosclerotic lesions are characterized by migration of macrophages, proliferation of smooth muscle cells, and abundant formation of fibrous, collagen, elastic fibers, and proteoglycans as connective tissue matrices, as well as intra- and extracellular lipid accumulation. Because the lipid accumulation in the intima appears yellow and mushy, it is called arteriosclerosis. Although arteriosclerosis is only one type of arteriosclerosis, it is commonly referred to simply as arteriosclerosis due to its frequent occurrence and significant clinical relevance.