A Jyotirlinga or Jyotirling or Jyotirlingam is a shrine where Lord Shiva, an aspect of God in Hinduism is worshipped in the form of a Jyotirlingam or "Lingam of light." There are twelve traditional Jyotirlinga shrines in India.
It is believed that Shiva first manifested himself as a Jyotirlinga on the night of the Aridra Nakshatra, thus the special reverence for the Jyotirlinga. There is nothing to distinguish the appearance, but it is believed that a person can see these lingas as columns of fire piercing through the earth after he reaches a higher level of spiritual attainment.
The names and the locations of the 12 Jyotirlingas are mentioned in the Shiva Purana.These shrines are:

Somnath is the foremost of the twelve Jyotirlinga Shrines of Shiva. It is held in reverence throughout India and is rich in legend, tradition, and history. It is located at Prabhas Patan in Saurashtra in Gujarat.
Mallikārjuna, also called Śrīśaila, is the name of the pillar located ...more

Puran katha