While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid ?

Acid should be added to water but not water to the acid. Why ?

(a) What are the common names of . (a) CaOCl_(2) , and (b) Na_(2)CO_(3)10H_(2)O ? (b) Why should plaster of Paris be stored in a moisture-proof container? (c) Explain why, while diluting a concentrated acid, acid should be added to water and not water to the acid.

When concentrated acid is diluted, water should not be added to the acid. Why?