What all rituals are followed during the Chhath Puja and what is the significance behind them?

This year, the four-day high spirited vibes are going to begin from November 17th, which is the first day of the continuous praying and is known by the name of Nahaye Khaye, Followed by Lohanda and Kharna that are observed on the second day of the festival. It is on the third day that Sandhya Arghya is offered to the setting sun which culminates with devotees offering Usha Arghya to the rising sun on the very next and the last day of the rituals. The first day begins with the high spirit, where the devotees are supposed to take a bath in a lake or a stream before enjoying a sumptuous meal for the physical and spiritual cleansing. The second day is all about fasting where the mind and the body are taught self –control and help in detoxification. The main rituals begin on the third day of the pooja with the gathering and arranging of the offerings. The vratti (one who fasts) and the entire family then goes to the nearby pond or river to offer their prayers to the setting sun, where the devotees stand waist-dip into the freezing water and offer flowers and fruits to the setting sun. The ritual is concluded with reaching to the same river spot before the sunrise and again offering prayers and goodies and asking for blessings from the Sun God, who is known to ward off every type of illness, cleanse the spirit, exhibit the right path and give energy.
Also known by the name of Surya Shashti, chhath pooja is considered to be one the oldest ritual performing festivals of India, celebrated with peppy and devotional music, traditional sweets, color yellow and flowers, since this religious-cultural festival falls on the 6th day of the Shukla paksha of Hindu lunar month of Kartika, which is exactly 6 days post Diwali. Ancient texts like the Brahma Vaivarta Purana also mentions about the Chhath Pooja and its significance. The rituals can be performed by both male and female but mere married individuals qualifies to perform the rituals. The rituals revolving around preparing Prasad- holy food to offer and fasting during on the onset of the winters are considered to be one of the toughest rituals, where prayers are accepted by the Sun God and chhatii maaiya to take care of the wellness, prosperity, protection and unity of the family of the devotees.