Mahashiva Ratri is celebrated in Falgun Krishna Paksha. People also do fasting in this day. We pray our God Mahadev by offering him Bel Patra and flowers. We pour milk in the Shiv Ling. It is believed that those who worship him by pure heart, Mahadev will take away their all pains, sorrows and fulfil their wishes.
Mahadev is very kind. In scripture Shiva is called Mahadev because he is the father to each and every living creatures and non living substances. After worshipping Mahadev peace, love, discipline and a belief in ownself flows through everyone. Shivaratri means the night which is spent by worshipping Mahadev the whole night.
There are three stories regarding why we celebrate Mahashiva Ratri.
According to Bhagwat Purana, when the samundra manthan was done all the Gods and devils present there took everything like jwelleries and all but nobody took the poison. Then the poison started flowing through the water which killed most of the living creature. It became danger for the world and Gods thought it will be danger to the heaven also. So all the Gods came to Mahadev and asked for help. As we all know Mahadev is very kind, he drank all the poison by himself and saved the world. Mahadev is also known as Neelkanth because of the blue poison which was seen on his neck after drinking it. After this incident everybody praised Mahadev the whole night and gave him the name Devon ka dev ‘Mahadev’. So to remember this day and to pray Mahadev, this day was called Mahashiva Ratri and we celebrate it.
According to Linga Purana, Mahashiva Ratri is also celebrated as the birthday of Mahadev because he appeared in the form of Shiv Ling this day. According to the story, one day Brahman and Vishnu were arguing over the topic who is superior if both. It turned into a fight and the whole world felt it and got afraid. So all the Gods and Yogis went to Mahadev regarding the problem. So to solve this problem Mahadev appeared as Shiv Ling which has neither the start nor the end. Brahman and Vishnu were unable to say what that object actually was. They were told to find the start and end of that Jyotirling. So Vishnu became a pig and started digging the Earth and Brahman became a bird and flew to the sky. But both were unsuccessful to find its start and end. They knew Mahadev was superior than them so they started to pray Shiv Ling. When they were praying a sound ‘AUM’ was coming out of the Shiv Ling which made them surprised. In the right side of Shiv Ling there was A (अकार), in the left side the U(उकार) and in the middle the M(मकार). The A or Akar denotes solar system, U or Ukar denotes fire and the M or Makar denotes the Moon. Brahman and Vishnu became happy after seeing this and started praying Mahadev. Mahadev gave them blessings. So the day when Mahadev appeared as Shiv Ling is celebrated as Mahashiva Ratri.
According to Hindu religion, Mahadev and Parbati git married on this day so they are worshipped this day everywhere. On the occasion of Mahashiva Ratri people carry out the marriage of Shiva and Parbati to remember them. It is believed that Mahadev and Parbati got married in the Himalayas of Mandakini Triyogi Narayan. The fire which is still burning from Treta Yuga is the proof of the marriage. It is said that Mahadev and Parbati got married infront of that fire. It is also said that marrying here makes your married life the best one. It is believed that we apologise for each and every mistakes we did on this day infront of Mahadev and we are always forgiven because Mahadev is very kind.
So these were the three main stories on why we celebrate Mahashiva Ratri.