The origins of yoga have been speculated to date back to pre-Vedic Indian traditions; it is mentioned in the Rigveda, but most likely developed around the sixth and fifth centuries BCE, in ancient India's ascetic and ramaa movements. The chronology of earliest texts describing yoga-practices is unclear, varyingly credited to Hindu Upanishads. The Yoga Sutras of Patanjali date from the first half of the 1st millennium CE, but only gained prominence in the West in the 20th century. Hatha yoga texts emerged around the 11th century with origins in tantra.
Yoga gurus from India later introduced yoga to the west, following the success of Swami Vivekananda in the late 19th and early 20th century. In the 1980s, yoga became popular as a system of physical exercise across the Western world. Yoga in Indian traditions, however, is more than physical exercise; it has a meditative and spiritual core. One of the six major orthodox schools of Hinduism is also called Yoga, which has its own epistemology and metaphysics, and is closely related to Hindu Samkhya philosophy.
Many studies have tried to determine the effectiveness of yoga as a complementary intervention for cancer, schizophrenia, asthma, and heart disease. The results of these studies have been mixed and inconclusive, with cancer studies suggesting none to unclear effectiveness, and others suggesting yoga may reduce risk factors and aid in a patient's psychological healing process. On December 1, 2016, yoga was listed by UNESCO as an Intangible cultural heritage.
In Sanskrit, the word yoga comes from the root yuj which means "to add", "to join", "to unite", or "to attach" in its most common senses. By figurative extension from the yoking or harnessing of oxen or horses, the word took on broader meanings such as "employment, use, application, performance" (compare the figurative uses of "to harness" as in "to put something to some use"). All further developments of the sense of this word are post-Vedic. More prosaic moods such as "exertion", "endeavour", "zeal", and "diligence" are also found in Indian epic poetry.
There are very many compound words containing yoga in Sanskrit. Yoga can take on meanings such as "connection", "contact", "union", "method", "application", "addition" and "performance". In simpler words, Yoga also means "combined". For example, guyoga means "contact with a cord"; chakryoga has a medical sense of "applying a splint or similar instrument by means of pulleys (in case of dislocation of the thigh)"; chandryoga has the astronomical sense of "conjunction of the moon with a constellation"; puyoga is a grammatical term expressing "connection or relation with a man", etc. Thus, bhaktiyoga means "devoted attachment" in the monotheistic Bhakti movement. The term kriyyoga has a grammatical sense, meaning "connection with a verb". But the same compound is also given a technical meaning in the Yoga Sutras (2.1), designating the "practical" aspects of the philosophy, i.e. the "union with the supreme" due to performance of duties in everyday life
According to Pini, a 6th-century BCE Sanskrit grammarian, the term yoga can be derived from either of two roots, yujir yoga (to yoke) or yuj samdhau (to concentrate). In the context of the Yoga Sutras of Patanjali, the root yuj samdhau (to concentrate) is considered by traditional commentators as the correct etymology. In accordance with Pini, Vyasa who wrote the first commentary on the Yoga Sutras, states that yoga means samdhi (concentration).
According to Dasgupta, the term yoga can be derived from either of two roots, yujir yoga (to yoke) or yuj samdhau (to concentrate). Someone who practices yoga or follows the yoga philosophy with a high level of commitment is called a yogi (may be applied to a man or a woman) or yogini (traditionally denoting a woman).