Cholesterol is not really bad, but, as with many things, too much of it can cause problems.  You will find Cholesterol in all the cells of your body.  Your body needs and makes cholesterol in order to work correctly.  Your body uses cholesterol to make hormones, vitamin D, and substances that help you digest foods.  Cholesterol is a waxy, fat-like substance that is also found in foods you eat. 

Cholesterol is carried in something called lipoproteins thoughout your bloodstream . These lipproteins consist of fat and proteins. The fat (or lipid) is inside and the proteins are on the outside.

Two Types of Cholesterol

Two kinds of lipoproteins carry cholesterol throughout your body.  They are low-density lipoproteins (LDL) cholesterol and high-density lopoprotein (HDL) cholesterol.

LDL is called the “bad cholesterol”. Too much LDL in you body increases your risk of heart disease.

HDL is called “good cholesterol”. HDL moves cholesterol from other parts of your body to the liver, which removes the cholesterol from your body. Higher HDL cholesterol levels in the body correlate to a lower risk of heart disease.

Your body needs both cholesterols to function properly.

What Is High Blood Cholesterol?

High blood cholesterol is defined as too much cholesterol in the blood.  This condition is known, over time, to cause heart disease.  In fact, it is a major risk fator for heart disease.
For more information, go to:

http://www.nhlbi.nih.gov/health/public/heart/chol/wyntk.htm
http://www.nhlbi.nih.gov/health/dci/Diseases/Hbc/HBC_WhatIs.html