Nethra Tharpanam is a Hindu ritual performed to honor and appease the ancestors, particularly through offering water and sesame seeds while chanting sacred mantras. It is believed to help cleanse past karmas, bring peace to departed souls, and provide spiritual benefits to the performer. This ritual is often performed on specific days like Amavasya (new moon) or during Pitru Paksha, aiming to strengthen the bond between the living and their ancestors and seek their blessings for prosperity, health, and well-being.