Cholesterol is considered both a good and a bad molecule to have in your body. why?

Cholesterol is good for you an example is hdls is the good cholesterol. 
An example would be olive oil and avocados. Ldl's are the bad lipids or fatty acids an example, If you would make something with too much oils and an excessive amount of oil in the food. These would also would be Low-density-lipoprotein.

The answer should be a