Why do Indian woman wear a red dot on their forehead?

it's a bindi
red means the woman is married and black means she is not
it is an indian religious custom

Religion

It's called a bindi and is traditionally worn by Hindus and Jain Buddhists. It has a variety of interpretations and meanings to different people. In a Buddhist point of view, it's said to be the sixth 'chakra' (which is basically a psychic energy centre) which represents the third eye or concealed wisdom. To some, it's used to enhance natural beauty. However, I believe the most common reasoning is that it's where you focus your attention when meditating. Red also means love, beauty See More and family in Indian culture.

Hope this helps, sorry for the long explanation but culture and religion both really interest me c:

it's called a bindi. it has to do with their culture

It's cultural.