What is the significance of jyotirlinga?
The significance is that all the 12 Jyotirlingas are Swayambhu or self- manifested or self- existent. They are not man made or krittima. So, they represent Lord Shiva fully. And their greatness is unmatched.
In MatrikA Bheda Tantram, Lord Shiva says that in Kailasa there exists a Jyotirmaya lingam (or Jyotirlingam ) ( which is of course inaccessible to human beings ) , similarly on earth a corresponding lingam exists in Visweswara KAsi. And, similarly there 11 others at different places of India.
We can't see the most divine lingam that is there on the Kailasa mountain but we can definitely see ( & pray to ) the lingam ( that is in KAsi ) which Lord Shiva says as being representing the one-sixteenth potency of the Kailasa lingam.
So, this gives us a rough idea of the divinity and the unmatched greatness of the Jyotirlingams that are found earth and in particular that of the KAsi lingam.
Sri Shiva Uvacha:
YathA Jyotirmayam Lingam KailAsha Shikhare Mama | Tasyaiva ShodashAnsaikah KAshyAm Visweswarah Stithaha ||
Lord Shiva said:
( Hey Parameswari ), Just like there is a Jyotirmaya Lingam on top of Kailasa there is a Lingam at Visweswara Kasi , which is of one sixteenth potency of the lingam at Kailasa.
MAtrikA Bheda Tantram, Chapter 8, Verse 4.
Are these temples or just ling placed on ground?
These lingas came first, then came the temples and holy kshetras associated with them. So, the temples were built later.
The stories associated with these Jyotirlingams are found in several Puranas and i have seen questions and answers on quite a few of them on this site. So you can do a search.
Now, as to why there are exactly 12 such Jyotirlingams on earth and not one less or one more , i can't answer. But even i want to know the reason.
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