The most common type of heart disease results from atherosclerosis. Atherosclerosis is a type of arteriosclerosis. Arteriosclerosis is a general term describing any hardening and loss of elasticity of medium or large arteries. Atherosclerosis comes from the Greek words athero (meaning gruel or paste) and sclerosis (hardness). It's the term for the process of fatty substances, cholesterol, cellular waste products, calcium and fibrin (a clotting material in the blood) building up in the inner lining of an artery. The buildup that results is called plaque. You can see in the visual above that arteries become narrowed because  of fatty deposits.