Kartika shukla tritiya is the third day of Kartika masa and is mainly famous as Sodari tritiya (Sodari means Sister). On Bhratri dwitiya , sister has to respect her brother. On the next day brother has to respect his sister so it is called as Sodari tritiya.
On the occasion of Bhratri dwitiya, the brother who was honoured by his sister, has to honour his sister on this day. According to his financial status, brother has to offer Sare (means kumkum, turmeric powder, blowse or saree) and gifts to his sister. This is the main ritual on this day.
Bhratri dwitiya and Sodari tritiya are the festivals to strengthen love, affection between family members and also gives a message about the value of relations to next generation. These are famous in the north India.
According to Chatur varga chintamani, people has to perform Vishnu Gowri vratham on this day. In this vratha, one has to worship Godess Lakshmi, invite a married woman and offer Sare, food to her. In some books it is given that, people has to perform Trilochana Gowri vrata on this day.
Lord Vidyashankara temple (Sringeri) celebrations will also start on Karthika shukla tritiya. Aradhana festival and Radhotsavam will be conducted for seven days ie. from Karthika shukla tritiya to Karthika shukla Navami.