In Hinduism, the God Shiva is the divine aspect that regenerates all life on earth. Brahma, Vishnu and Shiva together form the holy trinity of Creation, Preservation and Destruction or Regeneration.
So, after the discarding of all material goods and the dying of plants, animals and people, Shiva creates new conditions for new life forms. During Mahashivaratri, ‘the great night of Shiva’, Hindus worship Him intensely.
Mahashivaratri is celebrated in February or March (depending on the Hindu lunar calendar) in the night preceding the night of the new moon, when the moon is in-between the sun and the earth and thus least visible.
There is a new moon 29 or 30 days, as the moon goes around the earth every 29.53 days relatively to the sun. So each month in the lunar calendar has a Shivaratri. The Shivaratri in the first spring month Phālguna is considered holier than those in other months and thus named Maha Shivaratri. (Phālguna is the 12th and last month of the lunar year. To make sure the first month of the lunar year starts around the 14th or 15th of April, the start of the Hindu solar year, there is a complex system of extra months (Adhika Māsa) and lost months (Kshaya Māsa), because the lunar year only has about 356 days.)
The moon, symbol of mind and emotions, diminishes in power significantly every month (of the lunar calendar, where each month starts at a full moon) during the 14th night, when the moon is least visible. By devoting such a night to God in passionate worship, one shows the intense longing to overcome the mind. As then the mind and therefor also the intellect and ego are less powerful, meditation is more intense.
Devotees of Shiva fast on this day, meditate during the night and sing bhajans to honor Him. They also worship the Shivalingam by offering Bilva leafs (three-leafed leaves of the Bilva tree), milk and water. The Shivalingam (linga means symbol in Sanskrit) is the symbol of the form-less and omnipresent God.
According to Baba, Shiva/Shakti (the male and female aspect of Shiva) is present in every human. We should honor the Shiva/Shakti in each human by treating everyone with love and respect. He also says that when you make one step to God, that God will make a hundred steps to you. Mahashivaratri is a very suitable night to make a step to God in your effort to make progress on the spiritual path.