Hindus themselves do not know what this means. I certainly do
not; it is worn nowadays as a cultural symbol with minor religious
overtones. Indian Christians, Jains, Parsis, and Sikhs also often
wear the ``bindi'' on their forehead.
If anyone offers an interpretation, it is likely to be a modern one
that is not based in tradition.
In strictly religious ceremonies, many Hindus place some
other symbol on their forehead as a sign of their faith.
Among South Indian Vaishnavas, it is common for men and
women to both wear sri churnam (a vertical red line) on
religious occasions. The sri churnam represents the
presence of God's grace in the form of the Divine Mother
South Indian Saivas also tend to wear vibhuti (sacred ash)
on religious occasions, or when visiting the temple. However,
this is usually not to the exclusion of the bindi.