Maha Shivratri, as the name suggests, is in the honour of Lord Shiva, the third lord of the Trinity (Bramha-- the creator, Vishnu--the preserver and Shiva - the destroyer).
As the legend goes, 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.
When is Maha Shivratri celebrated?
This festival is celebrated in the month of Phagun, around a fortnight before Holi (which usually falls on a full moon night in February or March), as a homage to Lord Shiva. This festival also celebrates the union of Lord Shiva with Parvati.
The legend behind the union
Lord Shiva's first wife was Sati. Sati's father, King Daksha, opposed her 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.
Lord Shiva is offered special food, made from fruits of the season, root vegetables and coconuts, during ritual worship. The Shivling (phallic symbol of the Lord) is bathed with the panchagavya (five sacred offerings of a cow including milk, sour milk, urine, butter and dung). Thereafter, milk, butter, curd, sugar and honey, (believed to be the foods granting immortality), are offered. Dhatura and jati, though poisonous fruits, are sacred to Shiva and therefore placed in front of him.
Unmarried girls are supposed to perform the Maha Shivratri pooja with great faith. They pray to the lord for eligible husbands. Moreover, married women pray to Lord Shiva for for marital bliss and a long prosperous married life
Why is the Belpatra so important to Shiva?
Legend has it that one night Lord Shiva's devotee, a hunter, lost his way in the forest. As he was wandering in the night, he heard a tiger growl. The frightened man scurried up the nearest tree that was a Bel tree. He spent the night up there, out of the reach of tigers. To keep himself awake, he kept plucking and dropping Bel leaves while chanting the name of Lord Shiva. The next morning, when the devotee climbed down, he had unknowingly dropped thousands of leaves on a Shiva linga. The night-long worship pleased Lord Shiva who saved the hunter from the clutches of a tiger. This legend is recited on every Maha Shivratri.