The Karwa Chauth fast is traditionally observed without food or water from sunrise until the Moon is sighted. Women prepare for the evening puja by arranging a decorated thali with items like a diya, karwa, sieve, flowers, and sweets. The puja involves worshipping deities such as Goddess Parvati and Lord Shiva, listening to or reciting the vrat katha, and offering prayers to the Moon. The fast is completed after the Moon-sighting ritual, which often includes looking at the Moon and then at their husbands through a sieve.