What is the difference between good and bad cholesterol?

LDL (low-density lipoprotein) is called bad cholesterol because it deposits cholesterol into artery walls, forming plaques that narrow and harden arteries, increasing the risk of heart attack and stroke. HDL (high-density lipoprotein) is called good cholesterol because it acts as a scavenger, picking up excess cholesterol from the bloodstream and artery walls and carrying it back to the liver for removal from the body. High LDL levels are dangerous, while high HDL levels are protective. Diet, exercise, genetics, and lifestyle all influence these levels. Foods high in saturated and trans fats tend to raise LDL, while regular physical activity and healthy fats from sources like olive oil and fish tend to raise HDL.