Apolipoprotein A (ApoA) is a protein that plays a crucial role in lipid metabolism and is a major component of high-density lipoprotein (HDL). It helps transport cholesterol from the tissues back to the liver for excretion or recycling, which is essential for maintaining healthy cholesterol levels in the body. There are different forms of ApoA, with ApoA-I being the most abundant and well-studied. High levels of ApoA-I are associated with a lower risk of cardiovascular diseases, as it promotes the removal of excess cholesterol and reduces the formation of arterial plaques.