Cholesterol is a waxy, fat-like substance your body needs to build cells and make hormones. Your liver makes most of it; some comes from food. Because it doesn't dissolve in blood, it travels on carriers — chiefly LDL ("bad") and HDL ("good").
Too much LDL can build up as plaque in artery walls, narrowing them and raising the risk of heart attack and stroke. High cholesterol usually causes no symptoms, so it is found through a blood test. Levels often rise after menopause as estrogen falls. See high cholesterol in women and how to lower cholesterol.