The Linga Purana states , "Shiva is Nirguna Nirakaar ", which means ,"Shiva is signless, without color, taste, smell, that is beyond word or touch, without quality, motionless and changeless". Lingam is a Sanskrit word which means a symbol. A Lingam or Shivlingam is a representation of Nirguna Nirakaar Shiva . The devotess of Lord Shiva worship Him in the form of Shivlingam.
A Jyotirlinga is the holiest representation of Lord Shiva. A Jyotirlinga is a "Swayambhu" and self-manifested Shivlingam. There are 12 Jyotirlingas in Bharat collectively called as "Dwadash Jyotirlinga" , these Jyotirlingas are considered as the most sacred Jyotirlingas. It is believed that Lord Shiva manifested himself for his devotees in the form of Jyotirlinga in these 12 places. It is said that if a person visits all these holy shrines, he attains moksha. Each of these twelve Jyotirlingas are different manifestations of Lord Shiva. These Jyotirlingas take the name of the presiding deity.
Dwadash Jyotirlinga in Shiva Purana
Somnath
सौराष्ट्रदेशे विशदेऽतिरम्ये ज्योतिर्मयं चन्द्रकलावतंसम्।
भक्तिप्रदानाय कृपावतीर्णं तं सोमनाथं शरणं प्रपद्ये॥[ref]
Who to offer his devotion, in the most beautiful and serene Saurashtra region (Kathiawad) mercifully incarnated, the moon is the ornament on whose head, I go under the shelter of Lord Shree Somanatha in the form of Jyotirlingam.
Mallikarjuna Swami
श्रीशैलशृङ्गे विबुधातिसङ्गे तुलाद्रितुङ्गेऽपि मुदा वसन्तम्।
तमर्जुनं मल्लिकपूर्वमेकं नमामि संसारसमुद्रसेतुम्॥[ref]
Which is higher than the ideal mountains of height, on the summit of Srisailam, where there is a great meeting of the gods, live happily and Who is like a bridge to cross the world-ocean, I salute that one Lord Mallikarjuna.
Mahakaleshwar
अवन्तिकायां विहितावतारं मुक्तिप्रदानाय च सज्जनानाम्।
अकालमृत्योः परिरक्षणार्थं वन्दे महाकालमहासुरेशम्॥[ref]
To give salvation to the saints, Who has incarnated in Avantipuri (Ujjain), Mahadevji who is known by the name of Mahakal ,I salute you to avoid premature death.
Omkareshwar
कावेरिकानर्मदयोः पवित्रे समागमे सज्जनतारणाय।
सदैवमान्धातृपुरे वसन्तमोङ्कारमीशं शिवमेकमीडे॥[ref]
Who to bring the virtuous men across from the world-ocean ,near the holy confluence of Kaveri and Narmada ,He always resides in the Mandhatapura , I praise that unique benevolent Lord Omkareshwar.
Baidyanath
पूर्वोत्तरे प्रज्वलिकानिधाने सदा वसन्तं गिरिजासमेतम्।
सुरासुराराधितपादपद्मं श्रीवैद्यनाथं तमहं नमामि॥[ref]
Which is inside the Chitabhoomi (Vaidyanath-dham) in the north-east direction. Always reside with Girija, Gods and Asuras at whose feet the lotus feet are worshipped, I bow to that Shree Baidyanath.
Nageshwar
याम्ये सदङ्गे नगरेऽतिरम्ये विभूषिताङ्गं विविधैश्च भोगैः।
सद्भक्तिमुक्तिप्रदमीशमेकं श्रीनागनाथं शरणं प्रपद्ये॥[ref]
Which in the most delightful Sadang town of the South, endowed with various pleasures , being adorned with beautiful ornaments, Who is the only giver of bhakti and liberation, I take refuge in that Lord Shri Nagnath.
Kedarnath
महाद्रिपार्श्वे च तटे रमन्तं सम्पूज्यमानं सततं मुनीन्द्रैः।
सुरासुरैर्यक्ष महोरगाढ्यै केदारमीशं शिवमेकमीडे॥[ref]
Who is on the banks of Kedarshring near the Mahagiri Himalayas , always residing and worshiped by sages and the gods, demons, yakshas and great snakes etc., I praise that one benefactor Lord Kedarnath.
Trimbakeshwar
सह्याद्रिशीर्षे विमले वसन्तं गोदावरितीरपवित्रदेशे।
यद्धर्शनात्पातकमाशु नाशं प्रयाति तं त्र्यम्बकमीशमीडे॥[ref]
Who in the holy country of Godavari, resides on the Vimal summit of Sahyaparvat, Whose vision destroys the Patak immediately, I praise that Shree Trimbakeshwar.
Rameshwaram
सुताम्रपर्णीजलराशियोगे निबध्य सेतुं विशिखैरसंख्यैः।
श्रीरामचन्द्रेण समर्पितं तं रामेश्वराख्यं नियतं नमामि॥[ref]
Who , by Lord Shri Ramchandraji at the confluence of Tamrapari and Sagar, have been established by tying bridges of many arrows, I bow down to that Shri Rameshwar.
Bhimashankar
यं डाकिनिशाकिनिकासमाजे निषेव्यमाणं पिशिताशनैश्च।
सदैव भीमादिपदप्रसिद्दं तं शङ्करं भक्तहितं नमामि॥[ref]
Who is always served by demons in Dakini and Shakini Vrinda, I bow to the benevolent Lord Bhimashankar.
Kashi Vishwanath
सानन्दमानन्दवने वसन्तमानन्दकन्दं हतपापवृन्दम्।
वाराणसीनाथमनाथनाथं श्रीविश्वनाथं शरणं प्रपद्ये॥[ref]
I seek the protection of the Lord of the universe (Vishwanath) , Who lives is happily in the forest of joy, Who is the basis of all happiness, Who destroys all accumulated sins, Who is the lord of the city of Varanasi (kashi), and who is the lord of all who does not have anybody.
Grishneshwar
इलापुरे रम्यविशालकेऽस्मिन् समुल्लसन्तं च जगद्वरेण्यम्।
वन्दे महोदारतरस्वभावं घृष्णेश्वराख्यं शरणम् प्रपद्ये॥[ref]
Who sits in the picturesque temple of Ilapur , worshipped by the whole world, whose nature is very generous, I go in the shelter of that luminous Lord Shiva named Grishneshwar.
