Charak Puja venerates Shiva and Kali, symbolizing rebirth, absolution, and agricultural prosperity. It is observed on Chaitra Sankranti, the final day (April 14) of the Chaitra month, which is succeeded by the Bengali New Year.

During the Gajan festival, which is a week-long celebration starting in the last week of Choitro (the final month of the Bengali calendar) and continuing until the end of the Bengali year, devotees engage in various rituals. In Bardhaman, West Bengal, men dress in traditional outfits worn by Gajan sanyasis (Shiva devotees) to worship Shiva during the festival. Face painting is an important part of the festival, and devotees often have intricate designs painted on their faces, symbolizing spiritual devotion. Preparations for Charak puja, which usually begin a week in advance, involve gathering essential items such as paddy, oil, sugar, salt, and honey from village to village for the ritual. Gajan is celebrated to honour Shiva's union with Harakali, an incarnation of Goddess Parvati, while devotees dress up as mythological characters and perform on the streets, narrating their local folklore.