Maha Shivratri is celebrated on the new moon day in the month of Maagha according to the Hindu calendar. The day is celebrated to worship Lord Shiva, an important deity in Hindu culture.
During the night, Shiv Ling is given a holy bath every three hours. Fruits are also on offer for the god. There is also a tradition of listening to the Bhakti music and shlokas of Maha Shivratri and Lord Shiva. The idea is to understand its deep feeling. After this, a devotee breaks fast by consuming the prasad offered to Lord Shiva in the morning.
This is why unmarried girls keep fast on Shivratri:
On this day devotees worship Lord Shiva by offering Arakha crown flowers, water, milk and bhaang. Lord Shiva is considered as an ideal husband and to get a husband like him, unmarried girls and women worship him on this auspicious day by observing fast.
Shiv Purana says that if a devotee obeys Shivaratri fast with honesty, pure devotion and love, then he receives the divine grace of Lord Shiva.
According to Hindu mythology, following the observation of Mahashivratri fast, a devotee can help control two great natural powers, who suffer from a man, rajas (quality of emotional activity) and tamas guna (quality of inertia).
When a devotee spends the whole day at the feet of the god and performs it with all sincerity, then his/her anger is controlled and the evils like lust and jealousy are gotten rid of. Besides this, when a devotee wakes up at night, he also conquers the evils of tamas guna.
The devotees of Lord Shiva believe that the fast of Shivratri is auspicious and it has an equal or higher rating than doing Ashwamedh Yajna. Some people believe that devotees who observe Shivratri fast with honesty and chant the name of Lord Shiva, he/she becomes free from all sins. He is also free from the cycle of rebirth and death.
PNN