Cholesterol is a fatty substance present in the human body, 80% of which is manufactured by the liver. The other 20% comes from your diet such as meat, eggs and dairy products. There are two types of cholesterol, good cholesterol - HDL (High-density lipoproteins) and bad cholesterol - LDL (Low-density lipoproteins). High levels of LDL cholesterol present in the body enter the inner walls of the arteries and harden it. This version is the first release on CNET Download.com.