Kettu kalyanam is a tradition that is followed in the southern part of India, where two people who are going to get married tie a knot, that is called "kettu" or "mantra dhaarai".
When two people decide to get married, they go to a temple, and the priest there will perform the ceremony. The first step is called "Ponnoonjal," where the bride is made to sit on a wooden stool, and they offer turmeric water to wash her feet. This is done as a sign of respect and to purify the bride.
Then, the priest will perform some prayers and chants, and then they will introduce the groom to the bride. The groom will present her with a saree, which is known as "kodi vastram."
After this, the groom and the bride will sit on a mat made of banana leaves, and the priest will perform some more prayers and chants. Then, they will tie a knot that represents the union of their souls.
Once the knot is tied, the couple will exchange garlands, and they will become husband and wife. From now on, they will live their lives together, and they will support each other through thick and thin.
Overall, Kettu Kalyanam is a beautiful and important tradition in India that symbolizes the union of two souls in a holy bond of marriage.