Chhath Puja is a Hindu festival observed on Shashthi of Kartik Shukla Paksha. Primarily celebrated in the Terai regions of Bihar, Jharkhand, West Bengal, Eastern Uttar Pradesh, and Nepal, it is also known as Chhaith or Shashthi Puja.

Extending over four days, Chhath Puja involves the worship of Surya and Chhathi Maiya. Devotees observing the Chhath Puja fast undertake a rigorous 36-hour waterless fast as part of their religious observance.