Maha Shivratri is a Hindu festival celebrated every year in reverence of Lord Shiva.It is also known as padmarajarathri. Alternate common names/spellings include Maha Sivaratri, Shivaratri, Sivarathri, and Shivaratri.
Shiva-ratri literally means the great night of Shiva or the night of Shiva. It is celebrated every year on the 13th night/14th day of the Maagha or Phalguna month of the Hindu calendar.
Since many different calendars are followed by various ethno-linguistic groups of India, the month and the Tithi name are not uniform all over India and Nepal.
This festival is celebrated in the dark fortnight or Krishna Paksha(waning moon) of the month of Maagha according to the Shalivahana or Gujarati Vikrama or Phalguna according to the Vikrama era.
The festival is principally celebrated by offerings of Bael or Bilva/Vilvam leaves to Lord Shiva, all-day fasting and an all-night-long vigil. All through the day the devotees, chant the sacred Panchakshara mantra dedicated to Lord "Om Namah Shivaya". 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 summum bonum steadily and swiftly.
On Mahashivratri, Nishita Kala is the most perfect time to observe Shiva Pooja. On this day, in all Shiva temples, the most auspicious Lingodbhava puja is performed during this time. In Nepal, Pashupatinath Temple is very famous for celebration of Shivratri.