What is Cholesterol? where is it produced? What is its work? what disease is caused due to its lacking or it's abundance??

Cholesterol  is a type of fat found in your blood. Your liver makes cholesterol for your body. ... Meat, fish, eggs, butter, cheese, and milk all have cholesterol in them. Fruits, vegetables, and grains (like oatmeal) don't have any cholesterol.
The cholesterol in your blood comes from two sources: the foods you eat and your liver. Your liver makes all the cholesterol your body needs. Cholesterol and other fats are carried in your bloodstream as spherical particles called lipoproteins.