Yoga is a series of physical, mental and spiritual practices or disciplines which originated in ancient India with the view to attain a state of permanent peace of mind through the experience of one's true self. The Yoga Sūtras of Patañjali defines yoga as "the stilling of the changing states of the mind". Yoga can also be popularly defined as "union with the divine".
Various traditions of yoga are found in Hinduism, Buddhism and Jainism. In Hinduism, yoga is one of the six āstika schools (accepts authority of Vedas) of Hindu philosophy.Yoga is also an important part of Vajrayana and Tibetan Buddhist philosophy.
Pre–philosophical speculations and diverse ascetic practices of first millennium BCE were systematized into a formal philosophy in early centuries CE by the Yoga Sutras of Patanjali. By the turn of the first millennium, hatha yoga emerged from tantra. It, along with its many modern variations, is the style that many people associate with the word yoga today.
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. This form of yoga is often called Hatha yoga. Many studies have tried to determine the effectiveness of yoga as a complementary intervention for cancer, schizophrenia, asthma, and heart disease etc. etc. In a national survey, long-term yoga practitioners in the United States reported musculo–skeletal and mental health improvements.