01What Maha Shivaratri is
Maha Shivaratri, the great night of Shiva, is the Chaturdashi of the dark half of Phalguna (Magha in the south's reckoning), the night before the new moon at the end of winter. Of the twelve monthly Shivaratris it is the one the tradition marks as the greatest. It is kept with a fast through the day and a vigil through the night, divided into four prahar of worship.
02The story told of it
Several accounts gather on this night. It is held to be the night of Shiva's marriage to Parvati, the night he first appeared as an endless pillar of light before Brahma and Vishnu, and the night he held the halahala poison from the churning of the ocean in his throat, which turned it blue. In each the tradition sees Shiva's watch over the world while it sleeps.
03How it is kept
The day is a fast, many keeping only fruit and milk. Through the night the Shiva linga is worshipped in four prahar, each a quarter of the night, with water, milk, curd, honey, ghee and bilva leaves, and the mantra Om Namah Shivaya is chanted. The heart of the night is Nishita, around midnight. The fast is broken the next morning, after sunrise and before Chaturdashi ends.
04How the day is chosen
Maha Shivaratri is kept on the night Chaturdashi is current at Nishita, the muhurta around midnight. The night from sunset to sunrise is divided into four prahar for the four rounds of worship, and the fast is broken the next morning after sunrise, before Chaturdashi ends.
05Maha Shivaratri in other years