Maha Shivratri (the 'Great Night of Shiva') is a Hindu festival celebrated every year in reverence of Lord Shiva. Alternate common spellings includeSivaratri, Shivaratri, Sivarathri, and Shivarathri. It marks the convergence of Shiva and Shakti. Maha Shivratri is celebrated on the Krishna Paksha Chaturdashi of Hindu calendar month Maagha which falls in February or March as per the Gregorian calendar.
The festival is principally celebrated by offerings of Bael or golden apple or Bilva/Vilvam leaves to Lord Shiva, all-day fasting and an all-night-long vigil (jagarana). All through the day, devotees chant "Om Namah Shivaya", a sacred Panchakshara mantra dedicated to Lord Shiva. In accordance with scriptural and discipleship traditions, penances are performed in order to gain boons in the practice of Yoga and meditation, in order to reach life's highest good steadily and swiftly.
In Nepal, millions of Hindus attend Shivaratri together from different part of the world at the famous Pashupatinath Temple. Thousands of devotees also attend Mahasivaratri at the famous Shiva Shakti Peetham of Nepal.
On Mahashivratri, Nishita Kala is the ideal time to observe Shiva Pooja. Nishita Kala is the time when Lord Shiva appeared on the Earth in the form of Linga.  On this day, in all Shiva temples, the most auspicious Lingodbhava puja is performed.
jaagaram menas its a a ritual in Indian festiavals; On the diety of lord folklore prays for the entire night and doesnt sleep conducts puja chant veroms of lord shiva to get his blessings.
usually people vist Shiva temples on this aus pecious day;