Atherosclerosis is a chronic inflammatory disease where plaque builds up in the arteries, including the carotid, coronary, and femoral arteries. It involves the accumulation of fatty deposits and proteins in the artery wall over time. Left untreated, it can lead to serious complications like heart attack, stroke, and gangrene as the plaque restricts blood flow. Treatment options include carotid endarterectomy surgery to remove the plaque or carotid artery stenting, a minimally invasive procedure to open blocked arteries.