Chhath (also known as Dala Chhath) is an ancient Hindu festival dedicated to Surya (Sun), unique to Bihar and Jharkhand. Though Chhat is exclusive to Bihar, it’s also celebrated in Madhya Pradesh, Uttar Pradesh, some parts of West Bengal, Orissa, Assam, Chhattisgarh, the Tarai of Nepal, and even Mauritius, among the Hindi and Bhojpuri speaking people there.
The Mahābhārata has references to Draupadi, wife of the Pandavas, worshipping the sun, which was believed to help cure a variety of diseases, including leprosy, and ensure longevity and prosperity of family members, friends, and elders. In addition, it is believed that Chhath was started by Karna, the son of Surya, who became a great warrior and fought against the Pandavas in the Kurukshetra War.
It is celebrated twice a year: once in the summers (May-July), called the Chaiti Chhath, and once in the winter (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 arduous observance, requiring the worshippers to fast without water for more than 24 hours, is easier to undertake in the Indian winters.
Chhath is mainly a Bihari festival, and so it is celebrated wherever people from Bihar have migrated. This is a ritual bathing festival that follows a period of abstinence and ritual segregation of the worshiper from the main household for four days. During this period, the worshiper observes ritual purity, and sleeps on the floor on a single blanket. The main worshipers, called Parvaitin (from Sanskrit parv, meaning ‘occasion‘ or ‘festival‘), are usually women. However, a large number of men also observe this festival. The parvaitin pray for the well-being of their family, for prosperity and offspring. They can only perform Chhath if it is passed on to them from their older generation. However, once they decide to do it, it becomes their duty to perform it every year. The festival is skipped only if there happens to be a death in the family that year.
On the eve of Chhath, houses and surroundings are scrupulously cleaned. One the first day of the festival, the worshiper cooks a traditional vegetarian meal and offers it to the Sun God. This day is called Naha-Kha (literally, ‘Bathe and eat’!). The worshiper allows herself/himself only one meal on this day.
On the second day, a special ritual, called Kharna, is performed in the evening after Sun down. On this day also, the worshiper eats his/her only meal from the offerings (Prashad) made to the Sun God in this ritual. Friends and family are invited to the household on this day to share the prashad of the ritual. From this day onwards, for the next 36 hours, the worshiper goes on a fast without water.
The evening of the next day, the entire household accompanies the worshiper to a ritual bathing and worship of the Sun God, usually on the bank of a river, or a common large water body. The occasion is almost a carnival. Besides the main worshiper, there are friends and family, and numerous participants and onlookers, all willing to help and receive the blessings of the worshipper. Ritual rendition of regional folk songs, carried on through oral transmission from mothers and mothers-in-law to daughters and daughters-in-law, are sung on this occasion. The same bathing ritual is repeated on the following day at the crack of dawn. This is when the worshipper breaks his/her fast and finishes the ritual. Chhath being celebrated at the crack of the dawn on a river bank is a beautiful, elating spiritual experience connecting the modern Indian to his ancient cultural roots.
Source : Wikipedia