Moon worship is a request for welfare of the family by the women. 'Karva Chauth' is one such major festival of North India (Oct. 24, 2021). No food, no water for the day. Many men too fast along with their wives in support. Hindus in countries other than India will also celebrate this festivalAlso, many of the fasts end with sighting the new moon, or on specific phase of the moon (e.g., Ganesh Chaturthi on the fourth day).
It is a sort of women's day. A day before Karva Chauth women will have henna applied to their hands. The starts with the mother-in-law preparing food and gifts for the daughter-in-law
before the sunrise and the daughter-in-law reciprocating with gifts. In the evening married women will be in their best finery (bangles, necklaces, ear-rings, etc.) and would get together dance and sing. When the moon appears it is customary to first look towards moon through a sieve (was never able to understand the significance of this) and then similarly towards the husband. The husbands will then offer a glass of water to the wife, and then the feast begins (all vegetarian).
Karva Chauth - Wikipedia
Karva Chauth 2020 - Google Search
Videos also of people celebrating it.