Why do we celebrate Shivratri – Reasons for observing Mahashivaratri?

Shivaratri, or Mahashivratri, is one of the most important days in Hinduism. There are numerous reasons regarding the origin of Shivaratri and most of reasons for observing Shivratri can be traced to the Puranas. A few important legends are detailed below.

Origin of Shivratri based on hunter unknowingly dropping Bilva leaves on Shiva Lingam
There once lived a tribal man who was a hunter and a staunch a Shiva devotee. He used to go for hunting on all days to feed his family. One day the hunter lost his way while hunting and was trapped in the forest at night.
Soon wild animals started to gather around him and he climbed a Bel or Bilva tree. Sitting there he remembered his wife and children and tears started rolling from his eyes. In order to keep himself awake, he started plucking Bilva leaves and dropped it down repeating ‘Om Namah Shivaya’ – the Panchakshari Mantra. The hunter unknowingly fasted the whole day and did not sleep in the night.
In the morning, he discovered that he had been dropping the Bilva leaves on a Shivlingam. The Shivling was also washed with his tears.
He returned home and when he was about have his food, a beggar came at his door. The hunter fed the beggar and then had his food.
The beggar was Lord Shiva himself and the hunter had darshan of Bholenath and was able to feed Mahadeva, who feeds all the living beings.
And the hunter realized the beggar was Shiva when he died and was carried to the Shivaloka.
The hunter was later born as King Chitra Bhanu who could remember his previous births. And he discussed the importance of Shivaratri with Sage Ashtavakra.
The story is mentioned in the Shanti Parva of Mahabharata by Bhismha while on the bed of arrows after the 18-day Great War in the Mahabharata. Thus the world came to known about the importance of Mahashivaratri.

Origin of Mahashivaratri based on Samudra Manthan – Churning of Ocean
This is a famous legend on Shivaratri and happened during the churning of ocean by Devas and Asuras to get ‘Amrit.’ While churning the ocean, highly toxic poison, Halahala, came out and threatened to destroy the universe.
Lord Vishnu asked the ‘devas’ and ‘asuras’ to approach Lord Shiva and request to save the world.
Lord Shiva immediately agreed to help them and drank the poison. For the poison to have no effect, Lord Shiva should not sleep. So the ‘devas’ and ‘asuras’ kept praying the whole night. Pleased with the devotion Lord Shiva said ‘whoever worships me on this day will get their wishes fulfilled.’ (There is another version to this story in which Goddess Parvati stops the poison from spreading by holding Shiva’s neck)
Origin of Shivaratri based on Lord Vishnu and Lord Brahma searching for the origin of Shiva Lingam
It is impossible to find a beginning and end to the Supreme Being until and unless the Supreme Being wishes to incarnate in a form which human eyes can accommodate.
Apart from these important legends, it is said that the reunion of Lord Shiva and Parvati happened on the Shivratri day. Another legend states that Lord Shiva performed the Taandava on this day.
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