Maha Shivaratri is celebrated over three or ten days based on the Hindu luni-solar calendar. Every lunar month, there is a Shivaratri (12 per year).
The main festival is called Maha Shivaratri, or great Shivaratri, which is held on 13th night (waning moon) and 14th day of the month Phalguna.

A festival of contemplation
During the Vigil Night of Shiva, Mahashivaratri, we are brought to the moment of interval between destruction and regeneration;
The Ardha Marta (:) in ‘AUM:’ Kara.
it symbolizes the night
when we must contemplate on that which watches the regeneration out of the degeneration.

During Mahashivaratri be alone with the Shiva within us.
Be a ‘witness’ to the thoughts and the breath. Inhale (Ham), exhale (Sa)
Hamsa(Swan) filters the milk from the water, filters that which is required from abundance.
encourages to unite ourselves with the Collective Consciousness in Yoga.

Maha Shivaratri is considered the day when adiyogi or the first guru awakened his consciousness at the material level of existence.
According to Tantra, at this stage of consciousness, no objective experience takes place and the mind is transcended.
The meditator transcends time, space and causation.
It is regarded as the dark night of the soul, when the yogi attains the state of Shoonya or Nirvana, the stage preceding samadhi or illumination.

Maha Siva Rathri is also the night of Siva Tandavam - The Cosmic Dance.

Shiva Tandava is described as a vigorous dance that is the source of the cycle of creation, preservation and dissolution.

The Tandavam takes its name from Tandu (taṇḍu), the attendant of Shiva, who instructed Bharata Muni (author of the Natya Shastra) in the use of Angaharas and Karanas modes of the Tandava at Shiva's order.

The dance is a pictorial allegory of the five principle manifestations of eternal energy:
* Srishti - creation, evolution
* Sthiti - preservation, support
* Samhara - destruction, evolution
* Tirodhana - illusion
* Anugraha - release, emancipation, grace

Thus Tandava symbolizes the cosmic cycles of creation, sustenance and destruction, of microcosm and macrocosm.

AUM: Na Ma Si Va Ya

May the vigil tonight empty us ( Rudra Thandavam) and illuminate the soul ( Ananda Thandavam) to realise the ‘Siva within us’ with the Grace of Sivam itself.