The Sanskrit word nāthá or नाथ, is the proper name of a siddha sampradaya (initiatory tradition) and the word itself literally means "lord, protector, refuge". The related Sanskrit term Adi Natha means first or original Lord, and is therefore a synonym for Shiva, Mahadeva, or Maheshvara, and beyond these supramental concepts, the Supreme Absolute Reality as the basis supporting all aspects and manifestations of consciousness.
The Nath tradition is a heterodox siddha tradition containing many sub-sects. It was founded by Matsyendranath and further developed by Gorakshanath. These two individuals are also revered in Tibetan Buddhism as Mahasiddhas (great adepts) and are credited with great powers and perfected spiritual attainment.
The Natha Sampradaya Template:Lang-mr is a development of the earlier Siddha or Avadhuta Sampradaya, an ancient lineage of spiritual masters. Its founding is traditionally ascribed as an ideal reflected by the life and spiritual attainments of the guru Dattatreya, who was considered by many to have been a human incarnation of Lord Shiva. The establishment of the Naths as a distinct historical sect purportedly began around the 8th or 9th century with a simple fisherman, Matsyendranath (sometimes called Minanath, who may be identified with or called the father of Matsyendranath in some sources).
One story of the origin of the Nath teachings is that Matsyendranath was swallowed by a fish and while inside the fish overheard the teachings given by Shiva to his wife Parvati. According to legend, the reason behind Shiva imparting a teaching at the bottom of the ocean was in order to avoid being overheard by others. In the form of a fish, Matsyendranath exerted his hearing in the manner required to overhear and absorb the teachings of Shiva. After being rescued from the fish by another fisherman, Matsyendranath took initiation as a sannyasin from Siddha Carpati. It was Matsyendranath who became known as the founder of the specific stream of yogis known as the Nath Sampradaya.
Matysendranath's two most important disciples were Caurangi and Gorakshanath. The latter came to eclipse his Master in importance in many of the branches and sub-sects of the Nath Sampradaya. Even today, Gorakshanath is considered by many to have been the most influential of the ancient Naths. He is also reputed to have written the first books dealing with Laya yoga and the raising of the kundalini-shakti.
There are several sites, ashrams and temples in India dedicated to Gorakshanatha. Many of them have been built at sites where he lived and engaged in meditation and other sadhanas. According to tradition, his samadhi shrine and gaddi (seat) reside at the Gorakhnath Temple in Gorakhpur. However, Nityananda stated that the samadhi shrines (tombs) of both Matsyendranath and Gorakshanath reside at Nath Mandir near the Vajreshwari temple about a kilometer from Ganeshpuri, Maharashtra, India.
The Natha Sampradaya does not recognize caste barriers, and their teachings were adopted by outcasts and kings alike. The heterodox Nath tradition has many sub-sects, but all honor Matsyendranath and Gorakshanath as the founders of the tradition.
The twelve traditional Natha Panthas
The Natha Sampradaya is traditionally divided into twelve streams or Panths. According to David Gordon White, these panthas were not really a subdivision of a monolithic order, but rather an amalgamation of separate groups descended from either Matsyendranath, Gorakshanath or one of their students. According to the Shri Amrit Nath Ashram website, the twelve Natha Panthi are as follows:
- Satya natha
- Dharam natha
- Daria natha
- Ayi Panthia
- Vairaga kea
- Rama ke
- Ganga nathi
- Rawal ke
- Paava panth
- Paagala panthi
However, there have always been many more Natha sects than will conveniently fit into the twelve formal panths. Thus less populous sannyasin sub-sects such as the Adinath Sampradaya or Nandinatha Sampradaya are typically either ignored or amalgamated into one or another of the formal panths.
Modern Natha lineages
A recent modern Natha of the Adinath Sampradaya was Shri Gurudev Mahendranath (1911-1991), who received initiation in 1953 from H.H. Shri Sadguru Lokanath, the Avadhut of the Himalayas. In 1978, he founded the International Nath Order in order to make the Natha way of life available in the West. He wrote many essays and articles, some of which were collected as The Scrolls of Mahendranath, first published in 1990. His successor, Shri Kapilnath, continues to teach and initiate sincere seekers.
The Chitrakut Math parampara, made famous in the modern times by Shri Madhavnath Maharaj is currently being led forward by Shri Mangalnath Maharaj, who succeeded Shri Madhavnath Maharaj and has a large following. Shri Mangalnath Maharaj has established a Machindranath temple and Ashram at Mitmita, near Aurangabad, Maharashtra.
However, it can be safely paraphrased from Shree Nath Deepa-Prakash (Preface ;line14;7th edition) which directly contradicts the above statement. On 15th May' 1935 the Padukas of Maharaj were consecrated at Indore temple. On that occasion, he was questioned on appointment of a successor to carry forward the work of Nath Paramapara, he instantly replied "Nobody has given me this position, nor will I leave it for anyone." He further stated that a trust be formed to look after the Nath-Karya.
The Natha Sampradaya is an initiatory Guru-shishya tradition. Membership in the sampradaya is always conferred by initiation (diksha) by a diksha-guru—either the lineage-holder or another member of the sampradaya whose ability to initiate has been recognized by his diksha-guru.
The Natha initiation itself is conducted inside a formal ceremony in which some portion of the awareness and spiritual energy (shakti) of the Guru is transmitted to the shishya (student). The neophyte, now a Nath, is also given a new name with which to support their new identity. This transmission or "touch" of the Guru is symbolically fixed by the application of ash to several parts of the body.
- "The passage of wisdom and knowledge through the generations required the mystic magick phenomenon of initiation, which is valid to this day in the initiation transmission from naked guru to naked novice by touch, mark, and mantra. In this simple rite, the initiator passes something of himself to the one initiated. This initiation is the start of the transformation of the new Natha. It must not be overlooked that this initiation has been passed on in one unbroken line for thousands of years. Once you receive the Nath initiation, it is yours throughout life. No one can take it from you, and you yourself can never renounce it. This is the most permanent thing in an impermanent life."
The aims of the Nathas
According to Paul Eduardo Muller-Ortega, the primary aim of the ancient Nath Siddhas was to achieve liberation or jivan-mukti during their current lifespan. According to a recent Nath Guru, Shri Gurudev Mahendranath, another aim was to avoid reincarnation. In The Magick Path of Tantra, he wrote about several of the aims of the Naths,
- "Our aims in life are to enjoy peace, freedom, and happiness in this life, but also to avoid rebirth onto this Earth plane. All this depends not on divine benevolence, but on the way we ourselves think and act." 
- Shri Bhambhulnath - late abbot of the Nath Siddha monastery at Haridwar
- Shri Gurudev Mahendranath - final Guru of the Adinath Sampradaya
- Nisargadatta Maharaj (1897-1981) - past master of the Navnath Sampradaya
- Satguru Sivaya Subramuniyaswami - a past Guru of the Nandinatha Sampradaya
- Shankar Maharaj - a Nath Avadhuta
- Shri Madhavnath Maharaj (1857-1936)
- Sri Akshunnanath Mahaprabhu (Lord Sri Akshunna) - Nath master of Alakh Puri.
- Sri Avedyanath - abbot of the Gorakhnath Math 
- Bodhinatha Veylanswami - Sannyasin and Satguru of the Nandinatha Sampradaya
- Sri Kapilnath - current head of the Intl. Nath Order of Shri Mahendranath
- Shri Naharinath - current master of the Shri Amrit Nath Ashram
- Sri Narayan Nath - a householder Nath who is the current head of the Vairag-panth 
- Shri Mangalnath Maharaj - Currently anointed at the spiritual seat of Chitrakoot 
- Sri Yogi Matsyendra Nath - Sannyasin and kanphata belonging to the Dharma Panth. Russian origin, has his own web site Nathas' Tradition
- Deshpande, M.N. (1986). The Caves of Panhale-Kaji. New Delhi: Archaeological Survey of India, Government of India.
- Mahendranath (1990), Notes on Pagan India
- White, David Gordon (1996). The Alchemical Body. Chicago: University of Chicago Press.
- Shenoy, Gopalkrishna. Discipleship
- Bandyopadhyay, P. K. (1992). Natha Cult and Mahanad. page 73, Delhi, India: B.R. Publishing Corporation.
- Mahendranath, Shri Gurudev. The Ultimate Promulgation & Pronunciamento of H.H. Shri Gurudev Mahendranath in The Open Door: Newsletter of the International Nath Order, originally published in Mahendranath (1990).
- Mahendranath (1990), The Phantastikos
- Muller-Ortega, Paul Eduardo (1989). The Triadic Heart of Shiva. Albany, NY: State University of New York Press.
- Mahendranath (1990), The Magick Path of Tantra
- Shirvaikar, V. V. Yogiraj Shri Shankar Maharaj
- Adityanath (2002). Nath FAQ. Retrieved Oct. 20, 2004.
- Davisson, Sven (2003). Shri Kapilnath Interview in Ashé: Journal of Experimental Spirituality, Vol. 2, No. 4, Winter 2003.
- Gold, Daniel and Ann Grodzins Gold (1984). The Fate of the Householder Nath in History of Religions, Vol. 24, No. 2 (Nov., 1984), pp. 113-132.
- Mahendranath, Shri Gurudev (1990). The Scrolls of Mahendranath. International Nath Order. Retrieved Mar. 6, 2006.
- Mahendranath, Shri Gurudev. The Tantrik Initiation in The Occult World of a Tantrik Guru. International Nath Order. Retrieved Nov. 18, 2006.