Cholesterol is a fat like substance found only in animal products. Cholesterol alone is not very soluble in blood, so it is carried in the bloodstream by molecules called lipoproteins. Lipoproteins are named based on their density.
Triglycerides are another fat like substance in the body.
The liver makes cholesterol. In general, the higher the saturated fat content of the diet, the more cholesterol made by the liver. The cholesterol in the food we eat contributes very little to the blood cholesterol level. The level of triglycerides in the blood stream - the statistical correlation between blood triglyceride level and heart attack risk is not as strong as the statistical correlation between the blood cholesterol level and heart attack risk. The level of homocysteine in the blood stream - this is an amino acid made from the breakdown of protein in the diet, and has recently been recognized to be as important as cholesterol in statistically predicting the risk of a heart attack.