Every month in Krishna paksha chathurdhasi (fourteenth moonday) is called masa Shiva rathri. The one that comes in the month of "Masi" (mid 
February to mid March) is called Maha Shiva rathri. This is considered as the most important vrata by the devotees.
There are many incidents like this told in our Puraanas. If we do the vrata with pure devotion and love there can be no doubt about getting the Grace of the Almighty.
Once Lord Vishnu and Lord Bramha argued over each other’s prowess. However, Lord Shiva challenged both of them. He appeared as a flaming Linga and challenged the duo to measure the gigantic Linga (phallic symbol of Lord Shiva). Lord Bramha, who took the form of a swan, and Lord Vishnu who became a boar and went to Netherland, were both unable to measure the Shivlinga. Then Lord Shiva came out of the Linga and declared himself the most powerful. Maha Shivratri therefore means the grand night of Shiva. The devotees of Shiva fast during this day and pray to the lord throughout the night. This legend goes to prove the supremacy of Mahadev over other Hindu Gods.
King Daksha, opposed Sati's marriage with Shiva. At a yagnya (holy sacrifice) the king ignored Shiva’s presence and thereby insulted the latter publicly. Sati was so angered by this that she jumped into the sacrificial fire and ended her life. Lord Shiva unleashed his fury at the death of his wife by performing the violent dance, Taandav. He wiped out Daksha’s kingdom, undertook rigorous penance and retired to the Himalayas. The Gods, who feared that the severity of Shiva’s penance might bring an end to the world, revived Sati in the new avatar of Parvati. Shiva-Parvati married and this reunion is celebrated on Maha Shivratri.
There are many incidents told about the greatness of this day. Once a hunter in a jungle after searching throughout the jungle, was quite tired and could not get any animal. In the nightfall a tiger started chasing him. to escape from that he climbed a tree. That was a Bilva tree. The tiger sat under the tree waiting for him to come down. The hunter who sat on a branch of the tree was quite tense and didn't want to sleep. He was plucking the leaves and putting down as he was not able to be idle. Below the tree there was a Shiva lingam. The whole night went on like this. God was pleased with the Upavasa (hunger) and the Pooja the hunter and the tiger did even without knowledge. He is the peak of the grace. He gave the hunter and the tiger "Moksha".
In a Shiva temple on a Maha Shiva rathri day the lamp kept in the altar was very dim. That time a mouse which came take its prey touched the flame. Due to the heat it moved its head immediately. In the process it kindled the lamp and the altar was illuminated well. Lord Shiva, pleased by this deed made the mouse Mahabali, the renowned asura king.
February to mid March) is called Maha Shiva rathri. This is considered as the most important vrata by the devotees.There are many incidents like this told in our Puraanas. If we do the vrata with pure devotion and love there can be no doubt about getting the Grace of the Almighty.
Once Lord Vishnu and Lord Bramha argued over each other’s prowess. However, Lord Shiva challenged both of them. He appeared as a flaming Linga and challenged the duo to measure the gigantic Linga (phallic symbol of Lord Shiva). Lord Bramha, who took the form of a swan, and Lord Vishnu who became a boar and went to Netherland, were both unable to measure the Shivlinga. Then Lord Shiva came out of the Linga and declared himself the most powerful. Maha Shivratri therefore means the grand night of Shiva. The devotees of Shiva fast during this day and pray to the lord throughout the night. This legend goes to prove the supremacy of Mahadev over other Hindu Gods.
King Daksha, opposed Sati's marriage with Shiva. At a yagnya (holy sacrifice) the king ignored Shiva’s presence and thereby insulted the latter publicly. Sati was so angered by this that she jumped into the sacrificial fire and ended her life. Lord Shiva unleashed his fury at the death of his wife by performing the violent dance, Taandav. He wiped out Daksha’s kingdom, undertook rigorous penance and retired to the Himalayas. The Gods, who feared that the severity of Shiva’s penance might bring an end to the world, revived Sati in the new avatar of Parvati. Shiva-Parvati married and this reunion is celebrated on Maha Shivratri.
There are many incidents told about the greatness of this day. Once a hunter in a jungle after searching throughout the jungle, was quite tired and could not get any animal. In the nightfall a tiger started chasing him. to escape from that he climbed a tree. That was a Bilva tree. The tiger sat under the tree waiting for him to come down. The hunter who sat on a branch of the tree was quite tense and didn't want to sleep. He was plucking the leaves and putting down as he was not able to be idle. Below the tree there was a Shiva lingam. The whole night went on like this. God was pleased with the Upavasa (hunger) and the Pooja the hunter and the tiger did even without knowledge. He is the peak of the grace. He gave the hunter and the tiger "Moksha".
In a Shiva temple on a Maha Shiva rathri day the lamp kept in the altar was very dim. That time a mouse which came take its prey touched the flame. Due to the heat it moved its head immediately. In the process it kindled the lamp and the altar was illuminated well. Lord Shiva, pleased by this deed made the mouse Mahabali, the renowned asura king.
