This photograph is of Swami Dandapani. No, I am not a Sales Agent for him but am posting this here to illustrate something else. If you were to ever meet me in the mornings when I am at Pune, you will see me with the same kind of Vibhuti horizontal stripes on my forehead as well as the tilak just above the nose and between the two eyebrows.
These two applications indicate that I follow Shaivism. The horizontal lines are symbolic of inevitable destruction of the body as the material used is ash from our sacred fires. Ash is symbolic of the human body becoming ash after cremation. When one applies the ash on his body, one remembers that he is subject to becoming ashes.
The tilak is more important for this post. The spot where it is applied is called the Ajna Chakra in yoga. The material used is either sandalwood paste or kumkum powder or both. I use both. Applying this on one’s forehead during morning prayers is to invoke the earnest request to open the third eye of the individual, which would enable him to differentiate between the real and the unreal, or the permanent and the impermanent.