Karwa Chauth is an annual ritual mostly observed in Northern India sometime in October or November before Diwali on Kartik ki Chauth, or the fourth day of the Hindu month of Kartik (fourth day of the waning moon).

Fasting by day, praying and breaking the fast in the evening after sighting the moon, are the basic Karwa Chauth rituals. It is believed that the fasting ritual associated with this day is essentially to put a woman's fidelity, selflessness, and self-restraint to test. In earlier times, the elders of the family made use of such occasions to instill those qualities in the young wives.

There is a legend associated with the significance of Karwa Chauth. The story goes that Viru, a young woman who had kept a fast on Karwa Chauth, went to visit her parents, and her doting brothers could not bear to see her starve. So they lit a fire in the faraway woods, made her see it through a sieve as was the custom, and convinced her it was the moon.

Hungry and relieved, she willed herself into believing this rather obvious trick and agreed to break her fast. The first morsel of food that she tried to eat had a stone in it, the second a strand of hair, and by the time she got to the third, news reached her that her husband had slipped into a death-like coma.

On reaching there, her husband eventually woke up, but refused to accept Viru as his wife, and condemned her to the role of a maid. After years of torment and penance, she was restored to her rightful place as his wife.

Though the climax of the story is obviously biased and prejudiced, a part of it reinforces the concept of whole-hearted sacrifice and devotion between husband and wife.