According to Hindu Religion, every Brahmin should wear a mark on his forehead known as Tilak. Applying Tilak on forehead is a ritual in India. Right from the very ancient times in India, tilak is the most important part of our indian culture. From Raja’s to sages, everyone has worn tilak on their forehead.

Tilak, Trikund, Tika or Bindiya etc, directly relates to our brain. Right in between the two eyebrows, Tilak is worn. As described in Hindu Religion books and sculptures, in this very place, Aagya Chakra is situated. Concentrating on this point, i.e, on the center of our both the eyes, makes the person mentally strong and can control his thoughts by this continuous process. From this part of our head, all thought process of our brain is controlled. In one sense, it is also known as third Eye or it behaves like the third eye.
By applying Tilak on our forehead, we initialize and start our third sense, which acts like Radar of our body. Once again, it is also regarded as a respect given to a person as per hindu religion.
Scientific Aspect of applying Tilak as accepted by Hindu Religion
We use our brain extensively sometimes, which leads to pain in this area due to continuous pressure of thinking. Applying Chandan or Turmeric to this part daily, after bathing, makes it less vulnerable to headaches. It helps us reduce head pain. It is also found that, those who apply Chandan Tilak regularly on their forehead, are getting fewer headaches. It somewhat negates it. This is even regarded by Doctors and Vaidyas.