First let us understand what a jyothirlinga is: The jyothirlinga shrines are places where Shiva appeared as a fiery column of light. Originally there were 64 jyothirlingas while 12 of them are considered to be very auspicious and holy.
Each of the twelve jyothirlinga sites take the name of the presiding deity - each considered different manifestation of Shiva.At all these sites, the primary image is lingam representing the beginningless and endless Stambha pillar, symbolizing the infinite nature of Shiva.