Cholesterol is a type of fat (lipid) that circulates in your blood and plays an essential role in building cells and producing hormones. 

Low-Density Lipoprotein (LDL) cholesterol is often called the “bad cholesterol” because high levels can build up in your arteries, forming plaques that narrow blood vessels and increase the risk of heart disease, heart attack and stroke.

On the other hand, High-Density Lipoprotein (HDL) cholesterol is known as “good cholesterol,” as it helps carry excess cholesterol back to the liver for removal.