Lord Shiva is worshipped on the day of Krishna Chathurdasi that falls on the 14th night of the new moon. The Hindus offer their prayers to the the third deity of the Hindu trinity or the God of destruction- Lord Shiva who is also called by these alternate names- "Bholenath", "Neelakanth", "Shankar", Kailasheshwar", ‘Shambhu’, "Umanath", "Nataraj" and so on.
According to the mythological story -Shivratri (literally meaning the night of Shiva) is the night when he performed the Tandava Nritya or the dance of primeval creation, preservation and demolition. In the state of Kerala, the Sivarathri festival is celebrated in the month of Kumbham(February -March.) There are also other interesting mythological stories relating the powers of the Great Shiva.According to the Puranas, during the great legendary roiling of the sea water called Samudra Manthan, a container of poison (Kalakuda visham) emerged from the sea floor. This incident baffled the gods and the demons and they were horrified that the entire world could be destroyed .Then, only Lord Shiva saved this world by drinking the lethal toxin. But he stored the poison in his throat instead of consuming it completely. This made his throat turn blue, and since then he came to be known as Nilkantha, the one with the blue-throat. Shivratri celebrates this incident of saving the world by Lord Shiva.
On this auspicious day of Shivratri, a three-tiered pedestal is built around a fire. The uppermost piece of wood symbolizes swargaloka (heaven), the one at the centre represents antarikshaloka (space) and the bottommost plank symbolizes bhuloka (earth). Eleven kalash (metal urns) are placed on the swargaloka plank epitomizing the eleven manifestations of the Rudra Shiva. These planks are adorned with bael (woodapple leaves) and mango leaves at the top of a coconut typifying the head of Shiva with The rough shank of the coconut and the three circular marks on the fruit representing his tousled hair and the three eyes respectively. Six items are mandatory for the solemnization of MahaShivratri. They are the offering of calming bael leaves to the third deity of the Hindu trinity, representing purification of the soul; then the paste of vermilion is put on the Shivlinga after bathing it, thus representing virtue; offering of food which contributes to the prolonged existence and fulfillment of desires; burning of incense that results in increasing prosperity; the lighting of the diya or lamp contributes to the gaining of knowledge; and finally offering betel leaves to mark the fulfillment of mundane pleasures.
The offering of special pooja and abhishekhams, and the presentation of cultural programmes in all the Shiva temples celebrate the day.
The devout devotees fast rigorously all day long, intone the holy Panchakshara mantra "Om Namah Shivaya" and sing hymns in praise of the Lord Shiva. It is believed that one who devotedly chants the sacred name of Shiva during Shivratri with proper devotion is liberated from all sins and consequently from the repetitive cycle of birth and death. They offer flowers and incense to the God and the sound of incessant ringing of temple bells fills the place. They maintain long vigils during the night, keeping awake to listen to stories, hymns and songs. The fast is broken only the next morning, after the nightlong worship. MahaShivratri is also the prime attraction of the female folk. The married women pray for the happiness and health of their husbands and sons and the unmarried women pray for acquiring husband like Shiva, the ideal husband of Goddess Parvati. Sivarathri is celebrated with great pomp at the Siva Temple at Aluva on the sand bank of the River Periyar. Here, the Lingom (idol) of Siva that emerges out of the sand on the river bank.
The sand bank is extensive and the pilgrims running into several thousands congregate here. People belonging to all classes, castes and creeds assemble for this festival, some for worship, some for merchandise and some for sightseeing.
There are rows of sheds built where merchants exhibit every kind of merchandise for sale. There are shows, dances etc. meant for keeping the pilgrims awake throughout the night. In addition to the observance of MahaShivratri rites, most of the pilgrims offer Bali (sacrifice) to their ancestors in the morning succeeding the holy night.