The aim of Nāth yoga is liberation in this life (jīvanmukti) which is attained in a perfected or divine body (siddha/divya deha). The practice of developing the body (kāyā sādhanā) under the guidance of a guru, involves a long process of purification, Haṭha, and Kuṇḍalinī yoga which creates a ripe (pakva) body out of an unripe (apakva) one.
An oral tradition of songs in the vernaculars, especially Bengali and Hindī, praises the Nāth saints, and a written literature in Skt. describes yoga practice. Gorakhnāth is credited with writing the Haṭha Yoga, now lost, and the Gorakṣa Sataka. Other important texts of the Nāths are the Śiva Saṃhitā, the Gheranda Saṃhitā, the Haṭhayogapradīpika, and the Siddha Siddhānta Paddhati, which deal with yoga and the attaining of perfection in a perfected body.
The Nāth tradition still exists in India and has influenced other forms of Hinduism such as the Sant tradition, the Sahajīyās, and Indian alchemy (rasayāna).
"Nāth." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (February 19, 2019). https://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/nath
"Nāth." The Concise Oxford Dictionary of World Religions. . Retrieved February 19, 2019 from Encyclopedia.com: https://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/nath