The physical and chemical properties of fats depend on the nature of fatty acids. The fatty acids are grouped as saturated fatty acids and unsaturated fatty acids.
Saturated fatty acids in which all the carbon atoms are saturated with hydrogen atoms. Saturated fatty acids are found in abundance in naturally occurring fats.
Example: Palmitic acids, Stearic acid etc.
Unsaturated fatty acids in which all the carbon atoms are not saturated with hydrogen atoms. The unsaturated fatty acids have one or more double bonds
Example: Oleic acid, Linolenic acid etc.
  Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form fat. On the basis of nutritional value, the fatty acids are classified into two. They are essential and non essential fatty acids.