Chhath is mainly a festival celebrated in Bihar 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.
This is a ritual bathing festival which is celebrated for 3 days. During this period, the worshiper observes ritual purity, and sleeps on the floor on a single blanket. Once they decide to do it, it becomes their duty to perform it every year. In Hindu religion, sun is worshipped as a god and in Chath, the Sun God and the rivers are worshipped.
On the eve of Chhath, houses and surroundings are 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 (which means ‘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.
On the third day and main day devotees go to the rivers and ponds, singing folk and devotional songs and offering prayers to the rising sun. The same day the devotees also offer prayers to the setting sun.