Kalashtami, also known as Bhairava Ashtami, is a Hindu festival dedicated to Lord Kaal Bhairava, the fierce form of Lord Shiva. It falls on the eighth day (ashtami) of the Krishna Paksha (dark fortnight) of the moon in the Hindu calendar month of Kartik.

On this day, devotees observe a fast and worship Lord Kaal Bhairava by offering prayers, flowers, incense, and lamps. It is believed that by observing the fast and worshipping Lord Kaal Bhairava, one can seek his blessings for protection, prosperity, and fulfillment of desires.

The festival is particularly popular in parts of North India, especially in the state of Rajasthan, where elaborate processions and rituals are organized to celebrate Kalashtami. The day is also considered auspicious for performing special prayers and rituals for ancestors and seeking their blessings.