It is a symbol of their faith
They wear the Bindi, or dot on the forehead.
Women in India wear a red dot to represent a third eye which stands for knowledge, because of the goddess Shiva know as the destroyer.
It is called a "bindi."
sindhoor sindhoor
Indian men & women of the Hindu religion get a smudge of orange dust on their foreheads as a blessing. It is generally located where the "third eye" is.
Women in Hinduism often wear a red dot, known as a bindi, on their forehead, sometimes made of ruby or similar materials. The bindi can symbolize marital status, spirituality, or cultural identity. While traditionally red is common for married women, bindis can come in various colors and designs, reflecting personal style and fashion.
Bindi
A dot on the forehead is used in Asia by members of certain religions, such as Hinduism, as a religious sign of their devotion to their gods. The members of these religions would also wear these dots in the US and other non-Asian countries. But dots apparently are used in some gangs also. See the Related Link.
If you mean the sindoor on women's foreheads, no they are not. It is a washable, red powder.
No, women in Kerala do not wear sindoor. Wearing sindoor on the forehead is a North Indian custom.
In Hindu religion in India man use to put a straight line mark or a 'V' mark on their forehead which is known as TILAK which generall is formed by sandalwood paste, and which represent the god devotion, while women who are married put a dot on their forehead as the sign of their marrige.
For cultural, spiritual reasons.