High-density lipoprotein (HDL) is a type of cholesterol found in the blood that is often referred to as "good" cholesterol. It helps transport excess cholesterol from the arteries back to the liver, where it can be processed and removed from the body. Higher levels of HDL are associated with a lower risk of heart disease. HDL is one of several types of lipoproteins, which are particles made of fat and protein. Unlike low-density lipoprotein (LDL), which can lead to plaque buildup in arteries, HDL plays a protective role in cardiovascular health. Regular exercise and a healthy diet can help increase HDL levels.