The tilak, also known as the tilaka or tilakam, is a sacred mark worn by Vaishnavites on their forehead. It is a symbol of devotion and identification with Lord Vishnu and his avatars. The word "tilak" comes from the Sanskrit word "tila" which means sesame seeds, and it is believed that sesame seeds have purifying and protective properties.

The tilak is usually made with a paste of sandalwood, turmeric, and other sacred substances, and is applied in different shapes and sizes depending on the specific Vaishnavite tradition. It is typically worn in the center of the forehead, between the eyebrows, and can also extend to the nose or hairline.

One of the main reasons for wearing a tilak is to remind oneself and others of the ultimate goal of life, which is to attain moksha or liberation from the cycle of birth and death. The tilak is seen as a way to purify and prepare the mind for spiritual pursuits. It is believed that wearing a tilak helps to keep the mind focused on the divine and to overcome distractions and negative thoughts.

The tilak also serves as a mark of identification for Vaishnavites. It distinguishes them from followers of other traditions and serves as a reminder of their commitment to Lord Vishnu and his teachings. It is a way to publicly display one's faith and devotion.

In addition, the tilak holds deep symbolic significance in Vaishnavism. The three horizontal lines represent the three main deities of Vaishnavism - Lord Vishnu, his consort Goddess Lakshmi, and his vehicle Garuda. These lines also symbolize the three Gunas or qualities of nature - Sattva, Rajas, and Tamas. The red or yellow color of the tilak signifies energy, auspiciousness, and purity.

Moreover, the tilak is believed to have physical and spiritual benefits. The substances used in making the tilak, such as sandalwood and turmeric, have medicinal properties that can help to cool and protect the forehead from the harsh rays of the sun. Spiritually, it is believed that wearing a tilak can bring blessings and protection from the divine.

In conclusion, the tilak is an integral part of Vaishnavism, representing devotion, identification, and purification. It is a physical and spiritual reminder of the ultimate goal of life and serves as a way to connect with the divine. The significance of the tilak goes beyond its physical appearance, making it an essential aspect of Vaishnavite worship and practice.