Yoga as described in the Yoga Sutras of Patanjali refers to Ashtanga yoga. The Yoga Sutras of Patanjali is considered as a central text of the Yoga school of Hindu philosophy, It is often called “Rāja yoga”, “yoga of the kings,” a term which originally referred to the ultimate, royal goal of yoga, which is usually samadhi, but was popularised by Vivekananda as the common name for Ashtanga Yoga.
Ashtanga yoga incorporates epistemology, metaphysics, ethical practices, systematic exercises and self-development techniques for body, mind and spirit. Its epistemology (pramanas) is same as the Samkhya school. Both accept three reliable means to knowledge – perception (pratyākṣa, direct sensory observations), inference (anumāna) and testimony of trustworthy experts (sabda, agama). Both these orthodox schools are also strongly dualistic. Unlike the Sāṃkhya school of Hinduism, which pursues a non-theistic/atheistic rationalist approach,the Yoga school of Hinduism accepts the concept of a “personal, yet essentially inactive, deity” or “personal god”. Along with its epistemology and metaphysical foundations, the Yoga school of Hindu philosophy incorporates ethical precepts (yamas and niyamas) and an introspective way of life focused on perfecting one’s self physically, mentally and spiritually, with the ultimate goal being kaivalya (liberated, unified, content state of existence).