Chhath or Dala Chhath is a Hindu festival, unique to Bihar state, India and Terai, Nepal. This festival is also celebrated in the northeast region of India, Madhya Pradesh, Uttar Pradesh, and some parts of Chhattisgarh.

Chhath is a festival dedicated to the Sun God, considered to be a means to thank the sun for bestowing the bounties of life in earth and fulfilling particular wishes. Worship of the sun has been practiced in different parts of India, and the world from time immemorial. Worship of sun has been described in the Rig Veda, the oldest Hindu scriptures, and hymns praying to the sun in the Vedas are found.

In the ancient epic Mahabharata, references to worshipping of the sun by Draupadi, wife of the Pandavas, are found. It was believed that worshipping of the sun would help cure a variety of diseases, including leprosy, and also ensure longevity and prosperity of the family members, friends, and elders. It is also believed that Chhath was started by the great Danveer (alms giver) Karna, sired by the Sun God, who became a great warrior and fought against the Pandavas in the Mahabharata war.

Also called Dala Chhath - it is an ancient and major festival. It is celebrated twice a year: once in the summers (May-July), called the Chaiti Chhath, and once in the winters (September-November)around a week after Deepawali, called the Kartik Chhath. The latter is more popular because winters are the usual festive season in North India, and Chhath being an ardous observance, requiring the worshippers to fast without water for more than 24 hours, is easier to undertake in the Indian winters.