Chhath Puja is a Hindu festival dedicated to the worship of the Sun God, Surya, and Chhathi Maiya, who is believed to be the sister of Surya. This festival is predominantly celebrated in the Indian states of Bihar, Jharkhand, Uttar Pradesh, and the southern parts of Nepal.

Chhath Puja usually takes place six days after Diwali, and it is observed on the sixth day of the lunar month of Kartika according to the Hindu calendar. The festival spans four days, during which devotees perform various rituals and prayers.

Key elements of Chhath Puja include:

1. Nahay Khay (Day 1): Devotees take a dip in a holy river, and women observing the fast eat a single meal of rice and lentils.
2. Lohanda (Day 2): This day involves preparing the prasad (offering) and fasting throughout the day. The evening ritual includes the preparation of thekua (a special type of sweet) and the offering of the prasad to the Sun God during sunset.
3. Sandhya Arghya (Day 3 – Evening): Devotees gather on the banks of rivers, ponds, or other water bodies and offer prayers to the setting sun. This ritual is performed with offerings of fruits, sugarcane, and thekua.
4. Usha Arghya (Day 4 – Morning): On the final day, devotees gather before sunrise and offer prayers to the rising sun. This marks the conclusion of the Chhath Puja.

Chhath Puja is known for its rigorous fasting, stringent rituals, and the use of natural elements like water, sunlight, and fruits in the worship of the Sun God. The festival is significant not only for its religious aspects but also for its cultural and social significance, as it brings communities together in celebration.