Cholesterol is a fat that circulates in your blood. It mainly comes from two sources, first your body itself makes fat, regardless of what you eat. Second, it comes from the food that you consume. For your knowledge, only animal products contain cholesterol, food comes from plant do not contain cholesterol.
Cholesterol is carried in blood by special protein called “lipoproteins." Two types of lipoproteins are there: LDL (Low-density lipoproteins) referred as bad cholesterol, HDL (High-density lipoproteins) referred as good cholesterol. For better understanding, LDLs pick up cholesterol from the liver and carry it to the cells. HDLs get rid of excess cholesterol from the blood and take it back to the liver. A person's total cholesterol level is a combination of LDL and HDL cholesterol. Cholesterol can be checked by giving a blood sample in the lab; total cholesterol level shown in the result is a combination of LDL and HDL cholesterol.
Body produces enough cholesterol to stay healthy. But we end up eating too much fatty foods that can lift blood cholesterol levels which lead to heart diseases. Excess LDL or bad cholesterol gets deposited in the blood vessels; these deposits can join with other substances to form plaque which is a hard deposit in the blood vessel that can create blockage in the heart arteries.