Cholesterol is a type of fat that occurs naturally in your body and is also found in certain foods you eat. Your body needs some cholesterol to work properly, but if you have too much cholesterol in your blood, it can start to build up on the walls of your arteries, forming plaque. This buildup can narrow your arteries and make it harder for blood to flow through them, which increases your risk of heart disease or stroke.
Cholesterol levels refer to the amount of cholesterol present in a person's bloodstream. Doctors often measure cholesterol levels using a simple blood test called a lipid panel. The results are usually reported as milligrams (mg) of cholesterol per deciliter (dL) of blood, and the goal is to keep your total cholesterol level below 200 mg/dL.
There are two main types of cholesterol that doctors measure: LDL or "bad" cholesterol, which can raise your risk for heart disease if it's too high; and HDL or "good" cholesterol, which helps protect against heart disease when levels are high enough.
In summary, cholesterol levels refer to the amount of this fatty substance present in a person’s bloodstream, with higher levels potentially increasing one’s risk for cardiovascular diseases such as heart attack and stroke.