Karwa Mata, a form of Goddess Parvati associated with marital happiness, is worshipped alongside Lord Shiva, Ganesha and Kartikeya. Since Chaturthi is dedicated to Ganesha, prayers begin with him, followed by the final offering to the Moon. Moon worship is believed to bring marital harmony and ensure the husband's health and longevity. This year, Karwa Chauth falls on October 29.