you don't have to were it but it is concidered the trational dress 2 were if your a bangaldeshi or Hindu or Pakistani or south Asia and much more ... 2 find out more go and reaserach on...
Sari is a traditionally worn garment by Indian women. It is known that Hindu Goddess' (viz. Durga Devi, Lakshmi Devi,etc.) used to wear only sarees. So, women have been wearing sarees since that era....