Jyotirlinga or Jyotirling or Jyotirlingam is a shrine dedicated to Lord Shiva where Shiva is worshipped in the form of a Jyotirlingam or "Lingam of Light". There are said to be twelve Jyotirlinga shrines in India although their location is not consistently identified. The Jyotirlingas look like any other Shiva Linga. However, it is believed that a person who has attained a certain degree of spirituality sees these lingas as columns of fire piercing through the earth.
There are 12 famous Jyotirlingas where Lord Shiva appeared in the form of light (Jyothi) lingam. These have been worshipped from time immemorial. They are mentioned in the Dwadasa Jyotirlinga Stotra and are enshrined in following temples. Please click on the links to know more about the significance of each of these Jyotirlingas.
According to a legend of Lingodbhavamurthy narrated in Linga Purana, once Lord Vishnu and Lord Brahma were fighting to prove who was the Supreme Being. At this point, Lord Shiva appeared as a flaming Linga and challenged the duo to measure the gigantic Linga (phallic symbol of Lord Shiva). Brahma and Vishnu decided to find one end each and declared that whoever returned first would be acknowledged as supreme. Vishnu assumed the form of a boar and went down. Brahma, in the form of a swan, flew upwards. They searched for days but in vain and returned to the starting point exhausted and bewildered. At that moment, the central part of the pillar split open and Shiva revealed himself in his full glory. Brahma and Vishnu realized their mistake and acknowledged Shiva as the Supreme Being.
Since it was on the 14th day in the dark half of the month of Phalguna that Shiva first manifested himself in the form of a Linga, the day is especially auspicious and is celebrated as Mahashivaratri. Worshipping Shiva on this day is believed to bestow one with happiness and prosperity. Also read The Legend of Shiva Linga
Jyotirlinga shrines are held in great reverence in Hinduism. Puranas talk in detail about the significance of greatness of the Jyotirlingas. It goes on to say that by reciting the name of 12 Jyotirlinga a devotee can eliminate all the sins. Besides, the devotee becomes calm, chaste and pure as he becomes illuminated and enlightened with supreme and divine knowledge. The names mentioned for the benefits of all are:
Saurashtra Somnatham Cha Shrishaile Mallikarjunam ||
Ujjainyam Mahakalomkare Mammaleshwaram ||
Parlyam Vaijnatham Cha Dakinyam Bheem Shankaram ||
Setu Bandhe Tu Ramesham Nagesham Daruka Vane ||
Varanasya Tu Vishwesham Tribakam Gautamitate ||
Himalaye Tu Kedaram Ghurmesham Cha Shivalaye ||
Aetani Jyotirlingani Sayam Prataha Pathennaraha ||
Sapta Janma Kritam Papam Smaranen Vinashyati ||
Hindus believe that a sincere devotee who recites these 12 names regularly in the morning and evening washes all the sins committed in the previous seven births and attains all the powers and Siddhis.