Pradosh Vrat, also referred to as Pradosham, is a sacred bimonthly fast observed on the thirteenth lunar day (Trayodashi) of both the Shukla (waxing) and Krishna (waning) fortnights of each Hindu month. It is deeply dedicated to the worship of Lord Shiva and Goddess Parvati.
The name 'Pradosh' refers to the twilight period lasting approximately seventy-two minutes—about forty-five minutes before and twenty-seven minutes after sunset—when Trayodashi tithi prevails. According to Puranic legend, this is the auspicious window when Lord Shiva dances on Mount Kailash in ecstasy and drank the Halahala poison during the churning of the cosmic ocean to save the universe.
Depending on the weekday upon which Trayodashi falls, the fast acquires distinct spiritual significance and names, such as Soma Pradosham (Monday), Bhauma Pradosham (Tuesday), or Shani Pradosham (Saturday), the latter being particularly renowned for mitigating Saturnine afflictions.