Soaps are sodium or potassium salts of some long chain carboxylic acids. Sodium salts of fatty acids are known as hard soaps and potassium salts of fatty acids are known as soft soaps. Hard soaps are prepared from cheap oils, fats and sodium hydroxide. They contain free alkali and are used for washing purposes. Soft soaps are prepared from good oils and potassium hydroxide. They do not contain free alkali, produce more lather and are used as toilet soaps, shaving creams and shampoos. Soap is prepared by heating vegetable oil or animal fat containing Glyceryl stearate with concentrated sodium hydroxide solution. Hydrolysis of fat takes place and a mixture of sodium salts of fatty acids and glycerol is formed. The salts of fatty acids thus formed are used as soap. The alkaline hydrolysis of oils and fats forming soaps is commonly known as saponification.