Most religious Indians, especially married women wear a tilak or pottu on the forehead. It is applied daily after a bath and on special occasions before or after ritualistic worship or a visit to the temple. In many communities, it is enjoined upon married women to sport a kumkum mark on their foreheads at all times. The orthodox put it on with due rituals. The tilak is applied on saints and image of the Lord as a form of worship and in many parts of north India as a respectful form of welcome, to honor guests or when bidding farewell to a son or husband about to embark on a journey. The tilak varies in color and form. This custom was not prevalent in the Vedic period it gained popularity in the Puranic period. Some believe that it originated in South India. The tilak or pottu invokes a feeling of sanctity the wearer and others. It is recognized as a religion mark. Its form and color vary according to one caste, religious sect or the form the Lord worshipped. In earlier times, the four castes (based on varna or colour) – Braahmana, Kshatriya, Vaishya and Sudra – applied marks differently. The Brahmin applied white chandan mark signifying purity, as his profession was a priestly or academic nature. The kshatriya applied a red kumkum mark signifying valour as be belonged to the warrior. The Vaishya wore a yellow kesar or turmeric mark signifying prosperity as he was a businessman or trader devoted to creation of wealth. The Sudra applied a black bhasma, kasturi or charcoal mark signifying service as he supported the work of the other three divisions. Also Vishnu worshippers apply a chandan tilak of the shape of “U”, Shiva worshippers a tripundra (of the shape of “=”) of bhasma, Devi worshippers a red dot of kumkum and so on. The chandan, kumkum or bhasma which is offered to the Lord is taken back as prasad and applied on our foreheads. The tilak covers the spot between the eyebrows, which is the seat of memory and thinking. It is known as the Aajna Chakra in the language of Yoga. The tilak is applied with the prayer – “May I remember the Lord. May this pious feeling pervade all my activities. May I be righteous in my deeds.” Even when we temporarily forget this prayerful attitude the mark on another reminds us of our resolve. The tilak is thus a blessing of the Lord and a protection against wrong tendencies and forces. The entire body emanates energy in the form of electromagnetic waves – the forehead and the subtle spot between the eyebrows especially so. That is why worry generates heat and causes a headache. The tilak or pottu cools the forehead, protects us and prevents energy loss. Sometimes the entire forehead is covered with chandan or bhasma. Using plastic reusable “stick bindis” is not very beneficial, even though it serves the purpose of decoration. This custom is unique to Indians and helps to easily identify us anywhere.
"Why do we"- Swamini Vimalananda & Radhika Krishnakumar