The tilak is usually worn in the space between the eyebrows to mark the spot of the ajna (third eye) chakra.
There are three lines of a tilak and each represent various sacred trinities, such as the three sacred fires; the three syllables of the mantra, Aum; the three gunas; the three worlds; or the three gods, Brahma, Vishnu and Shiva.
Saivites believe that the three lines symbolize the three powers of Shiva: knowledge, will and action. In Vaishnavism, it is believed that the three vertical lines remind the wearer of the three gods, the three Vedic texts or the three realities.
Occasionally a tilak may be worn on other parts of the body parts such as the shoulders, chest or neck. It can be worn daily or for specific sacred rites and special occasions, depending on the local tradition.