This document discusses atherosclerosis, defined as a disease of arteries characterized by atheromatous plaques composed of lipid cores and fibrous caps. Risk factors include age, gender, genetics, hyperlipidemia, hypertension, smoking, diabetes, obesity, and inactivity. The response-to-injury hypothesis views it as a chronic inflammatory response to endothelial injury, involving modified lipoproteins, macrophages, and T-cells interacting with artery walls. Plaques can rupture, causing thrombosis. Unstable plaques with large lipid cores and thin fibrous caps are more vulnerable to rupture. Advanced lesions can rupture, bleed, aneurysm, or form fatty streaks composed of foam cells.