What are fillers and what role these fillers play in soap ?

Explanation

Substances which are added to soaps to change their properties in order to make them more useful for a particular application, are called fillers. For example,
(i) Sodium rosinate, sodium silicate, borax and sodium carbonate are added to laundry soaps to increase their lather forming ability.
(ii) Glycerol is added to shaving soaps to prevent them from rapid drying