The objective of this chapter is to introduce the fats. The term lipids are applied to a group of naturally occurring substances characterized by the insolubility in water, greasy feel and solubility in some organic solvents. They occur in the plant and animal kingdoms. Lipids more commonly known as fats and oil are integral part of our food. They are insoluble in water, but soluble in organic solvents. Fats are solid at 20°C they are called oils if they are liquid at that temperature. They are classified as simple lipids, e.g. triglycerides, compound lipids, e.g. phospholipids, derived lipids, e.g. cholesterol. This chapter covers the caloric value, properties of fats, recommended dietary allowances, dietary sources of fats, functions of fat in the diet, digestion and absorption of fats, essential fatty acids, lipids in blood, and deficiency of fats.